


A LABORATORY GUIDE 

FOR 

GENERAL BOTANY 

GAGER 




C££:lRIGHT DEPOSm 



A LABORATORY GUIDE 

FOR 

GENERAL BOTANY 
G A G E R 



BY THE SAME AUTHOR 



FUNDAMENTALS 

OF 

BOTANY 

i2mo, xix -f- 640 Pages, 435 Illustrations. Flexible 
Cloth, Round Corners, Si. 50 Postpaid. 

P. BLAKISTONS SON & CO., PHILADELPHIA 



A LABORATORY GUIDE 

FOR 

GENERAL BOTANY 



\i pi'- ^^ 

C" STUART GAGER 

DIRECTOR OF THE BROOKLYN BOTANIC GARDEN 



PHILADELPHIA 

P. BLAKISTON'S SON & CO. 

1012 WALNUT STREET 
1916 



<3K'5"3 
.G-3 



Copyright, 1916, by P. Blakiston's Son & Co. 



^0 



NOV 20 1916 



THE il^JPLE PHESS YOKKl FA. 



CU446500 



PREFACE 

This Laboratory Guide is intended for the use of 
students in their first course in universities and colleges, 
or other institutions doing work of similar grade. It is 
not a teacher's manual, and therefore does not include 
information as to laboratory equipment, the purchase and 
care of apparatus and materials, nor references to the 
literature. The author believes that botanical instruc- 
tion in America has now reached a stage where such 
directions to university instructors is no longer necessary 
nor appropriate. 

As to the most desirable kind of laboratory directions 
there is a wide diversity of opinion among teachers of ex- 
perience. This Guide has been prepared in harmony 
with the theory that the beginning student needs to learn, 
in his first laboratory course, not merely botanical facts, 
but how to observe and how to record his observations. 
It is believed that rather full directions, such as are given 
in the following pages, will accomplish this result. In 
advanced courses the student should, of course, be ex- 
pected to work with increasing independence, both in 
his thinking and his handling of apparatus and material. 
The Guide, substantially as here offered, has been used 
with a number of large beginning classes. 

The order of topics follows that in the author's Funda- 
mentals of Botany, but with only minor changes the 
Guide may be adapted for use with any text. 

The author is indebted to Dr. E. W. Olive for his care- 
ful reading of portions of the page proof. 

C. Stuart Gager. 

Brooklyn Botanic Garden, 
October 14, 1916 

V 



CONTENTS 

Page 

To the Student i 

PART I 

ANATOMY AND PHYSIOLOGY 

Meaning of the Terms 9 

A Generahzed Plant (Spirogyra) 1 1 

A SpeciaHzed Plant {e.g., The Bean Seedling) i6 

Structure of the Foliage Leaf 1 7 

Transpiration 22 

Absorption of Water by Plants 29 

The Path of Water in the Plant 34 

Mechanical Uses of Water in the Plant 36 

Nutrition 39 

The Occurrence of Carbohydrates in Plants 40 

Formation of Carbohydrates 45 

Alcoholic Fermentation 50 

Respiration 53 

The Influence of External Conditions on the Plant 56 

PART II 

MORPHOLOGY AND LIFE HISTORY 

Meaning of the Terms 59 

An Outline of the Classification of Plants 61 

Directions for Study 63 

Polypodium vulgare (Common polypody) 63 

Polytrichum commune (Common hair-cap moss) 74 

Marchantia polymorpha (A liverwort) 84 

Fucus vesiculosus (Bladder wrack) 96 

Vaucheria sessilis (Green felt) 102 

Spirogyra (Pond scum, Green silk) 106 

Pleurococcus vulgaris (Green slime) no 

Phycomyces nitens (or Rhizopus nigricans) 113 

Saprolegnia (Water mold) 117 

Albugo Candida (Blister blight) 121 

Agaricus campestris (Meadow mushroom) 125 

' vii 



Vlll CONTENTS 

Page 

Puccinia graminis (Wheat rust) 130 

Isoetes (Quill wort) 134 

Equisetum (Horsetail) 140 

Lycopodium (Club-moss) 144 

Selaginella (Little club-moss) 147 

Zamia floridana (A cycad) • • ^53 

Pinus laricio (Austrian pine) 161 

Trillium (Wake-robin) 177 



A LABORATORY GUIDE FOR 
GENERAL BOTANY 



TO THE STUDENT 

THE NATURE AND PURPOSE OF LABORATORY WORK 

A. The Laboratory: 

1 . The word laboratory is derived from the Latin word 
labor ^ meaning work. A laboratory, therefore, is a 
workshop. The essential part of laboratory work, 
however, is not the manual but the intellectual. 
HandHng specimens, manipulating apparatus, tak- 
ing notes, and making drawings, all are essential, 
but are wholly secondary to thinking. A laboratory 
exercise should be regarded always and primarily as 
a thought exercise. Everything else that you do 
with a specimen should be secondary to thinking 
about it, and done only to aid thought. 

2. The aim of laboratory work is to obtain facts at first 
hand. Reading books on plants is only studying 
about botany. To study botany one must have the 
actual plants before him. It was Louis Agassiz 
who said, " If you study nature in books when you 
go out of doors you cannot find her." The posses- 
sion of this first-hand knowledge makes the reading 
of botanical books not only more easy, but vastly 
more interesting. You can take more away from 
the text because you bring more to it. 



2 A L.\EOIL\TORY GUIDE TOR GE^■XR.AJ. BOT.AXY 

3. Another aim of laboraton' work, not less important 
than the one just mentioned, is to acquire 5::e":iic 
habits of thought and work; to ieorr. the ruethod by 
which kno~'edge of the given science is acquired. 
The scientihc method diners from the unscientiic 
in lading emphasis upon the absolute necessity of 
an orderly procedure in thinking and doing, upon 
Willingness to put asice prejudice and ureconceived 
notions, upon scrupulous neatness, accuracy of 
thought and v/ork. and careful attention to minute 
details. The scientinc method is not peculiar to 
the natural sciences: it is just as essentiai in history 
or language-study as elsewhere, and the highest 
success in any inteliectual pursuit is not possible 
if the requirements of the scientid.c method are dis- 
regaried. 

B. 0:o:^u:::■;^; 

4. Obser-"ati:n is not merely looking at a thing. It 
means looking for a purpose. Tne mental attitude 
of the true :": server is tn^t :: a questioner. The 
great Swiss botandst. de Can! die, Scio, ''The in- 
terrogation point is the key to all the sciences." 
Obsen-ation. then, consists in asking as dednite 
questions as possibie about natural objects, and 
seeking their answer, not from the instructor or 
the text-b: in, but from the object itseh. 

5. Remember that y:ur specimen is tne final authority 
in aU matters cf fact, Your first cuestion sho'old 
never be, "WTiat cu^':: I to see?"" ''How many 
parts aught the specimen to have?" but always, 
without exception. "What do I see?"" "Hew many 
parts does the specimen have?" Possibiy your 
specimen may be found to differ from that of }-:ur 
nei^bor. or from the descriptions in the bvi'^C'Ks. 



•* TO THE STUDENT 3 

If SO, record that fact, and endeavor to ascertain 
whether your specimen is abnormal, or whether 
your observation of it is at fault in any way. 
Always try to see all you can with the unaided eye 
before resorting to the aid of a hand lens or microscope. 
C. Experimentation: 

6. In mere observation one takes conditions as he finds 
them; in experimentation, he determines, within 
limits, the conditions under which the observation 
is made. It is never possible to control, absolutely, 
all the conditions in any experiment, but this is 

' partly compensated for by arranging side by side of 
the experiment proper, a check or control. In the 
experiment and control all conditions should be as 
nearly alike as possible save one. The golden rule 
in experimenting is: vary only one condition at a 
time. Then if the experiment and control give 
unlike results, we are justified in attributing the 
difference to the unhke factor. 

7. Before beginning an experiment, the object, or aim, 
of the experiment must be clearly conceived and 
clearly stated. The necessary materials and ap- 
paratus should next be decided upon and procured. 
Then may follow the operation, that is, the arrange- 
ment of the materials and apparatus in a suitable 
way. This step is frequently referred to as ''set- 
ting up" the experiment. The record of it should 
include an accurate statement of the conditions at 
the beginning of the experiment, together with 
drawings of the apparatus and material as the 
experiment is set up. 

Next follows the observation, which must always be 
made and recorded at the time and place of the experi- 
ment. It should include suitable drawings. Fin- 



4 A LABORATORY GUIDE FOR GENERAL BOTANY 

ally, there may be stated the inference, that is, the 
conclusion or conclusions which are thought to be 
justified by the facts observed. 

The record of an experiment, then, should follow 
the outline given below: 

1. Object. 

2. Materials and apparatus (with drawings). 

3. Operation. 

4. Observation (with drawings). 

5. Inference. 

6. Remarks. 
D. The Note-hook: 

8. The Note-book serves two purposes: First, the 
making of it gives you opportunity to acquire 
facility in describing what you observe. This is 
not an easy accompHshment, but a very essential 
one. ^^The greatest thing a human being ever does 
in this world/' said John Ruskin, "is to see somethings 
and tell what he saw in a plain way^ 

9. Secondly, the note-book serves as an index, to the 
instructor, of what you have done and how well 
you have done it. In addition to these two pur- 
poses, the note-book will be a permanent record 
for your own future use. It should contain a 
complete record of all you observe, and the infer- 
ences you make from these observations. It should 
include written descriptions and drawings. In 
both the latter the aim should be accuracy, neatness, 
completeness, conciseness. Above all things, it 
should be a record of your own observation, not 
of your neighbor's. If, as may happen on rare 
occasions, it becomes necessary to use your neigh- 
bor's notes, always state the fact clearly and frankly 
in your own book. 



TO THE STUDENT 5 

10. In writing your notes, the aim should be to give 
such a clear account of what you have seen and done 
that anyone else who knew nothing of the subject 
could profit by reading them. In other words, 
aim to make your notes usable in the future. Your 
text-book may be regarded in one sense, as the 
author's laboratory note-book. Seek to make 
your laboratory note-book an accurate and readable 
illustrated text on the ground covered by your 
course. 

E. Laboratory Drawings: 

11. Drawing is one of the greatest aids to observation. 
This is its main purpose in the laboratory. It 
is often said that "persons who cannot draw cannot 
see.'' This is probably an extreme statement, 
but it is undoubtedly true that one who can make 
an accurate drawing of a thing has observed it 
more accurately than one who cannot. 

12. Laboratory drawings should aim to represent the 
thing only as it is, not as it may impress one at 
first sight. They differ in this respect from the 
work of the artist. For example, to show the 
exact number and location of the veins of a leaf 
would ruin the artist's picture; but without those 
details the laboratory drawing would be of little 
value. 

13. As directed in the Guide, make as thorough an 
observation of the object as possible before you 
begin to draw; then make the drawing. 

14. Unless otherwise directed, make outline drawings, 
shading only where absolutely necessary. In 
general, every line in your drawing should represent 
some fact of structure in the specimen. 

15. Be sure to make the drawing large enough so that 



A LABORATORY GUIDE FOR GENERAL BOTANY 

all details may be included without crowding or 
confusion. 
i6. First sketch in the outline lightly with a 5H drawing 
pencil. In finishing a 2H pencil may sometimes be 
desirable. 

17. All drawings should be on unruled sheets, and only 
on one side of the sheet. They should be labeled 
and numbered consecutively throughout the course 
by writing under each the abbreviation Fig., 
followed by the proper numerals, and then by the 
legend or label, stating what the object is, and what 
view of it is shown, as for example, "Cross-section, 
end view." Each drawing should have all of its 
essential parts labeled by extending straight 
horizontal dotted lines from the various parts 
(using a ruler), and writing the name of the part 
at the end of the line. , 

18. The arrangement of the drawings on the page 
should receive careful attention, so as to make as 
attractive and well balanced a page as possible. 
Crowding should be avoided, and on any one page 
should be included only those drawings that repre- 
sent parts of the same plant, or pertain to the 
same subject. 

19. The various pages of drawings should be numbered 
and labeled near the top of the page at the middle 
thus; Plate I. Throughout your written notes, 
when describing a structure or apparatus repre- 
sented by a drawing, refer to the drawing by its 
proper number and the number of the Plate {e.g., 
Plate IV, Fig. 5). 

20. At the completion of the course, arrange a ^^Tahle 
of Contents,''^ listing the main topics, as indicated 
in the Laboratory Outline, in the order in which 



"" TO THE STUDENT 7 

they occur in the note-book, with the page number 
near the right-hand edge, and a neat dotted line 
extending from the subject to the page number. 
F. The Microscope: 

21. Full directions for the use and care of the compound 
microscope will be given by the instructor. The 
student should clearly realize from the first that the 
science does not reside in the instrument. The latter 
is merely an aid to the eyes, but not to the miq.d, 
and is made necessary by the limited range of our 
unaided vision. It should be used only after one has 
seen all that he possibly can with the unaided eye. 

22. The following points should be constantly borne 
in mind : 

{a) Keep all parts of the instrument, especially 

the lenses, scrupulously clean. 
[h] Never attempt to take the instrument apart. 

[c) Never remove lenses from the stand. If it 
is ever absolutely necessary to do so, then 

[d) Never lay a lens down on the table. 

[e) Never touch the lens with the fingers or eyelids. 
'/) Never try to clean the lens with the handkerchief 

or anything except lens paper, 
[g) Never examine any object without covering 

it with a cover-glass. 
'fi) Never allow the objective to touch the cover- 
glass. 
[i) Ne^er focus down while looking through the 

microscope, 
[k) Be sure that the slides and covers are absolutely 

clean. Dirt will be magnified as well as the 

object you are studying. 
[I) Handle all slides and cover-glasses by the edge, 

never touching their surface with the fingers. 



8 A LABORATORY GUIDE TOR GENERAL BOTANY 

(w) Don't shut one eye- when looking through 
the instrument. Ability to work with both 
eyes open is easily acquired, is much less 
tiring, and is an advantage in many ways. 

(«) Nercer use high powers zi'Iieji low powers will serve, 

{o) Examine all objects with the low power first, 
then with the high power, if necessary. 

(p) Never set the instrument away with a micro- 
scopic shde under the objective, nor with the 
high-power objective over the aperture. 

(q) When the laborator}^ period is over, remove 
the preparation you have been stud}ing, and 
leave the microscope with the low-power 
objective over the aperture. 



PART I 
ANATOMY AND PHYSIOLOGY 



I. Meaning of the Terms 

A . Plant physiology is that branch of botany which deals 
with the vital activities of plants. But physiological 
processes or functions are carried on by various parts 
of the plant, and these parts all have their own char- 
acteristic structure. In order to understand the proc- 
esses we must know the internal as well as the 
external structure of the parts concerned. This knowl- 
edge requires dissection, and this phase of the science 
is, therefore, called anatomy. Microscopic anatomy is 
called histology. Just as the processes cannot be 
intelligently considered apart from the structures 
involved, so, also, the study of anatomy apart from 
physiology is meaningless. 

B. In the lowest {i.e., most simply organized) plants all 
functions, both nutritive and reproductive, are per- 
formed by every structural unit or cell; but in more 
highly organized plants there are special parts or 
organs for the performance of each function; for ex- 
ample, roots to take in moisture, flowers to form seed. 
In other words, in the higher plants there is a division 
of physiological labor, or, as it is sometimes called, a 
physiological division of labor. While not entirely 
wanting, the division of physiological labor is less 
marked in the lowest plants. 

9 



lO ANATOMY AND PHYSIOLOGY 

Because they are composed of organs, plants and 
animals are termed organisms. 
C. Thus we see that some plants have a generalized plant- 
body, others a more highly specialized one. To under- 
stand the various life-processes carried on by plants, 
we must have a knowledge of their structure. A gen- 
erahzed plant will be studied first, then the structure 
of a higher {i.e., more highly specialized) plant. This 
will be followed by an elementary study of the funda- 
mental life-processes involved in the nutrition and 
growth of the indi\dduaL The second part of the 
course will be devoted to stud}dng the various kinds 
of plants, and the 'numerous ways in which different 
kinds of plants solve these same hfe-problems of nutri- 
tion and reproduction. 



II. A Generalized Plant {Spirogyra) 

A. Naked-eye Characters: 

1. Carefully take a small bit of this plant between the 
thumb and fingers and note its ''feel." Suggest 
why it is sometimes referred to as ** green silk." 

2. Carefully lift up some of the material with a needle, 
and describe the form of the plant. How many 
centimeters long are the longest filaments you can 
observe? 

3. Can you detect any evidences of a differentiation 
of the plant into shoot {i.e., stem and leaves) and 
root ? 

B. Microscopic Characters: 
I. The plant as a whole. 

(a) Mount two or three filaments in water. 

(b) Note that the filament is composed of separate 
structural units, placed end to end. These 
units are cells. 

(c) Are the filaments more than one cell thick? 
Do they branch? Are they of uniform diame- 
ter? Compare the length of the various cells 
with each other. Compare the shape of the 
end cell with that of the others. What is the 
shape of the filament as seen in imaginary cross- 
section? Very careful focussing is necessary in 
order to answer this question correctly. 

{d) Accurately measure the length (in millimeters) 
of a piece of filament lying straight under the 
cover-glass, then count the number of cells in 
. II 



12 ANATOMY A^~D PHYSIOLOGY 

this piece. Calculate the average length of the 
cells, and the number of cells in the longest 
filament observed. Estimate the length of an 
indL\idual cell in terms of its diameter^ and from 
this calculate the diameter of the filament. 
(e) Using the low power and remo\'ing the cover- 
glass, carefully cut a filament apart with the 
scalpel, causing as little injur\- as possible. As 
you do this observe the exposed end-walls of 
the uninjured cells that now terminate the fila- 
ment where it was broken apart. Describe and 
try to account for what you see. Is there any 
e^"idence of the existence of a force within the 
cell? If so, in what direction does it act? 
Make two outline drawings, showing the con- 
ditions before and after cutting. 
(/) Make a diagram about 75 mm. long, illustrating 
the outline of the three terminal cells of a fila- 
ment, as seen in optical section. Omit all de- 
tails of cell-structure. 
2. The indhidual cell. 

(a) Center your attention on any one of these cells, 
and identify the following organs of the cell : 
(i) A cell-wall, enclosing all other parts of the 
ceU. Is it transparent or not? Give a 
reason for your answer. Xote its relative 
thickness. The wall is composed of cellu- 
lose. Has each cell its own end-wall, or is 
there a common end- wall for two adjacent 
cells? 
(2) The substance enclosed by the cell-wall is 
largely ]i\Tng matter, or matter in the K\'ing 
state. It is called protoplasm. The unit 
of protoplasm of each uidi\idual cell is 



A GENERALIZED PLANT I3 

called a protoplast. Distinguish the follow- 
ing parts of a protoplast : 

(3) The prominent green chlorophyll-band, or 
chromatophore. Describe its form, the 
number of turns it makes in the cell, and 
the outline of its margin. Infer its shape 
in cross-section. How many in each cell? 
If more than one, do they coil in the same 
direction? Can you detect free ends of the 
chromatophore? Are they continuous from 
cell to cell? The color of the chlorophyll- 
band is due to the presence of a green pig- 
ment, chlorophyll. 

(4) The denser areas within the chromatophore 
are regions of starch-formation. In the 
center of this area is the starch-forming 
body, or p3rrenoid. Surrounding the pyre- 
noid are starch grains. 

(5) Make a detailed drawing, lo mm. wide and 
15 mm. long, showing the details of struc- 
ture of a portion of the chlorophyll-band, 
as seen under high power. Indicate on the 
drawing the names of all parts shown. 

(6) At or near the center of the cell find a dense, 
colorless body, the nucleus, surrounded by 
a less dense layer of colorless cytoplasm. 
Describe the shape of the nucleus. From 
the layer of cytoplasm trace 

(7) Delicate cytoplasmic strands, extending to 
the pyrenoids, and to 

(8) The lining layer of cjrtoplasm. This layer 
(sometimes called " primordial utricle") is 
in intimate contact with the entire inner 
surface of the cell-wall, and is difficult to 



14 ANATOMY AND PHYSIOLOGY 

identify. Its two surfaces are plasma 
membranes. 
(9) The clear spaces in the cell are vacuoles, 
filled with cell-sap. 

(10) Make a drawing of a cell at least 10 cm. in 
longest measure. 

(11) The lining layer may be easily demonstrated 
as follows: Place a drop of a 5 per cent, 
solution of common salt (sodium chloride) 
at one edge of the cover-glass. Be careful 
that none of the solution runs over onto the 
cover-glass. By placing a small piece of 
blotting paper at the opposite edge of the 
cover-glass, the water will be removed, and 
the salt solution drawn under the cover- 
glass, irrigating the specimen. Follow with 
another drop if necessary. Observation 
should be continuous while the specimen 
is being irrigated with the solution. 

(12) Describe the effect of the salt solution on 
the Hning layer. 

(13) Loosening the Hning layer, as above, is 
termed plasmolysis {i.e., loosening the plasm) . 
The cell is said to beplasmolyzed. 

(14) Make a drawing, the same size as the pre- 
ceding, showing a plasmolyzed cell. 

(15) Before plasmolysis the lining layer was held 
close against the cell-wall with a force, 
already detected (e, p. 12), sufiicient to 
cause a rigid condition of the cell called 
turgor or turgidity. 

(16) Now replace the salt solution with fresh 
tap-water, by the method described in (11) 
above. Describe the effect on the cell. 
What condition has been restored? 



A GENERALIZED PLANT 1 5 

Make a diagram, at least 25 mm. in diameter, show- 
ing the appearance of a cell in imaginary cross- 
section taken through the nucleus. 
Do you think Spirogyra is a unicellular or a multi- 
cellular plant? If the latter, how many cells con- 
stitute one plant? Give reasons for your opinion 
either way. 

Note. — If time permits, the study of cell-structure may be ex- 
tended by observing the cells in young leaves of Elodea, the skin 
(epidermis) of onion scales, the basal cell of the hairs on any seed- 
ling cucurbit, or the cells of the stamen hairs of Tradescantia. 



III. A Specialized Plant {e.g., The Bean Seedling)^ 

A. The plant as a whole: 

1. Examine the seedling given you and note that it is 
composed of an axis with appendages; the axis, of 
root and shoot; the root, of a primary root with 
branches (secondary roots); and the shoot, of a 
main stem, bearing leaves. Has the main stem 
branches? Is this true of all plants? What is the 
difference between a stem and a branch? 

2. Describe fully the location of the leaves and their 
attitude on the stem. Do they occur on both the 
main stem and its branches? The places on the 
stem where leaves grow are nodes. The spaces 
between the nodes (vertically) are called intemodes. 

3. Compare the size of the upper with that of the lower 
angle made by the leaves with the stem. This 
upper angle is called the leaf-axil (Latin axillay 
armpit) . 

4. Do you find any structures in the leaf- axils? If so, 
describe them. What are they? 

5. With what do the tips of the main stem and branches 
terminate? 

6. Describe any other outgrowths of stem or branches. 

7. Make a drawing of the plant as large as your draw- 
ing paper will permit, showing all parts referred to 
above. 

^ This study may or may not be omitted, depending upon the previous 
preparation of the students, and the time available. 



16 



IV. Structure of the Foliage-leaf {e.g., Lilac 

Leaf) 

A. External Characters: 

1. Make a drawing, natural size, showing all the parts 
of the foliage-leaf given you, as seen from the under 
side. 

2. Identify the following parts, and label them suit- 
ably on your drawing: 

{a) The flat, expanded blade. Describe its colora- 
tion {i.e., the kind and distribution of color). 
Is the blade simple (i.e., not divided into leaf- 
lets), or compound {i.e., branched, divided into 
leaflets)? The surface that lies uppermost, as 
the leaf bends back from its position in the bud, 
is the ventral surface; the under surface is the 
dorsal one. These terms are appHed with ref- 
erence to the position of the leaf in the bud. 

{b) The leaf-apex, which is also the apex of the 
blade. 

{c) The margin of the blade. 

{d) The base of the blade. 

(e) The venation (distribution of veins in the blade) . 
Describe it as parallel-veined, pinnateiy netted- 
veined (with a midrib), or palmately netted- 
veined. Describe the difference between the 
three types of venation. Is there a marginal 
vein? If so, suggest what advantage it may 
be to the leaf. 

(/) The petiole (stem of the leaf). Leaves having 

a petiole are petiolate, otherwise sessile. 
2 17 



i8 .osATomr assd fhvseoijogt 

(g) The leaf-base, the portion by which the leaf is 

attached to the branch. 
(A) n present, the stqpales, outgrowths of the kaf- 
': i 5 1 Leases without stqinles arc exs tipiilate . 
(i Z t: : :e :he next dass exercise compare -^.'.'z : ir 

ieai stuiiti ::.5 i::f::ti above, vari : u s ;:Jitr 

types ©: z? z- ;:Zt;:tf by yourself n:,^~^ 

fall drs~ii.^s iLivi ikoics. 



1. Ar iirriTti by the instructor, remove a 5tr!T> of 
'.-z 1; Ti epidermis of a foKage-lei: 3."i r:: jut 
it in watt: :: ilearing fluid, being si: t :; iii r :iz 
out^* siLriiif jppermost- Record .ir ririt 
the species. 

2. Mote tbe cdhdar structure of the eiMdennis. A 
gn>iq> of cefls, simiTar in structure and function, 
ds called a tissue. Tit leaf-epidemiis is epidermal 

tissue. The :tZ-~iL : : m? a box, having depth as 
well as lCTLg:i m ::7ii:i Mote that vou see 
only the edges :: :ir tr:i;il waDs. H;~ —iiy 
are thcae? Are there other waDs? If s ; i : ~ 
many? Are tbey visible? Eiplain. Ma^t i iii- 
gram of an epideimal cell as seen in po^pective. 
Are the ceQ-walls transparent or qpaque? (Hve 
a reason for your answer. Suggest the advantage 
of this feature to the plant. 

3. Obsove the someidiat lenticular opeoiii^, or 
pcHCS. escb purro^juded l?v creso^it-shaped ceDs. 

»Mjss EcxEKSC':^ J.-,- J:: . 46: 221-::^ 5: ::-?) has iBCMBinr- irf 

die lexves of the ffcl : —-ir ; !i--ts as sr-e-iii^;- s.i-.-rfs.rtOTy for tLt s: _ ly 

<tf the qiiili'M imfc;. az 1 2 ". : ~ i :.i r '^zz. ; "^ t : .- ''■■'*■> mn^ -77:1- 
miom, and Jirwilesr j : 



•^ STRUCTURE OF THE FOLIAGE-LEAF 1 9 

The openings are stomata (Latin singular, stoma, a 
mouth). The crescent-shaped cells are guard-cells. 
How many has each stoma? 

4. Do the guard-cells and other epidermal cells contain 
chlorophyll-bodies (chloroplasts) ? Describe their 
shape. They are not considered identical with the 
chlorophyll-band of Spirogyra, hence the different 
name. 

5. Note the shape and arrangement of the other 
epidermal cells. Are they in the same plane as 
the guard-cells? Describe, giving reasons for 
your answer. 

6. State the number of stomata visible in the entire 
field (high power). Record three counts, each 
of a different area, and the average. Why is this 
desirable? After ascertaining the area of the ob- 
jective of your microscope, calculate, from several 
counts, the average number of stomata per square 
centimeter. 

7. Make a drawing showing at least three stomata 
with their guard-cells and adjacent epidermal cells. 
The guard-cells should be at least 15 mm. long. 

THE UPPER EPIDERMIS 

8. As directed in B, 1-6 above, study the structure 
of the upper epidermis of the same leaf. Draw. 

9. Compare the structure of the upper with that of 
the lower epidermis, noting, among other features, 
the relative number of stomata in each. 

10. In the light of the experiments on transpiration,^ 
what do you think is one function of these stomata? 
Of the guard-cells? 

^ This takes for granted that class demonstrations of transpiration have 
been given. 



20 ANATOMY AND PHYSIOLOGY 

11. Owe one gqilanatioli of the diff<acnce in the rate 
<tf tnms|Hrati<m from the two surfaces of the leaf. 
Is this tibe only e^danatim? 

CROSS-SKCnONAI. VIEW 

12. Moimt free-hand sectioiis of a fresh leaf showing 
the intemal anatomy as seen in cross-section. 

13. Identify in your section the two ^idennal layers. 
How many cdk thic^ are they? Do you find 
any chloroidasts in these layers? 

14. Are an the qpidomal cdl-waDs of the same thick- 
ness? Describe any variations observed. 

15. Is there a thic^ continuous pdHde over the surface 
of the leaf? Is it composed of cells? Such a 
peHide, when it occurs, is called cuticle. 

16. Conqiaie the thickness of the cell- walls in the upper 
and the lowef epideonis. 

17. Hote the stomata and guard-ceUs^ and their relation 
to the otha- ^lidennal cdk. 

18. The tissue between the two epidermal layers is 
conqiosed chi^f of leaf-parenchyma, or mesophyll, 
in which are imbedded the veins. MesophyU, and 
an other tissue containing chlorophyll, whether 
found in leaves or in other organs, is also called 
ciilofCiicliTiiia. Note that the mesophyll is com- 
posed of two distinct groiqis of cdls, as follows: 

19. The more compactly lying cefls beneath the upper 
epidemub compose the pahsade layer, or palisade 
pgrencliyma. Describe their shape, contents, rela- 
tive size, and idation to each other and to the 
epidermis. 

20. B^ween this layer and the lower ^)idermis lies the 
spongy parenchyma. Describe its appearance, and 



STRUCTURE OF THE FOLIAGE-LEAF 21 

the cells that compose it. Compare it with the 
palisade layer. 

21. What fills the space between the mesophyll-cells? 
Do these spaces connect with the outside air? 
If so, how? 

THE VEINS 

22. At certain regions the section passes through veins, 
presenting either cross, longitudinal, or other 
sections of them. Note the greater differentiation 
of the cells in the veins. This differentiation marks 
the distinction between fundamental tissue or 
parenchyma, and transformed tissue, prosenchjrma. 
There are several different kinds of prosenchyma. 

23. Using prepared slides, supplied by the instructor, 
make a drawing of the cross-section of a leaf, show- 
ing all features noted above. Make the drawing 
at least 75 mm. long, and be careful to preserve the 
natural proportions. 

24. The experiments on transpiration have shown that 
living plants are constantly losing water. What 
would be the result if no more were supplied? 
What problem of plant life, therefore, naturally 
arises? 



V. Transpiration^ 



Loss of Weight of a Growing plant: 

Experiment i. — Object:^ To show that a living plant 
is constantly losing weight. 

I. Choose a well- watered, \dgorous, potted plant. 
Wrap the pot in sheet rubber or oilcloth (or paraf- 
fined paper), and tie the wrapping about the stem 
tightly, but not tightly enough to cause injury. 
Place the plant thus prepared on a pair of balances 
in a well-lighted window, and record its exact 
weight in grams in the following table, which should 



Time 


Weight in 


Day Hour 


grams 









be copied into your note-book, hittx weighing, 
the window should be opened (if the weather is not 
too cold) ; direct sunlight is also desirable. Record 

^ Note. — Where the class is large, or the laboratory equipment limited, 
and especially when the course extends over only one semester, it is rec- 
ommended that most, if not all, of the physiological experiments outlined 
in the remainder of Part I be performed by the instructor as demonstra- 
tions in the presence of the class. 

2 For directions for recording an experiment see p. 4 of this Guide. 
In each experiment this outline is to be filled out entire, without further 
directions. 

22 



TRANSPIRATION 2$ 

the weight at five or six successive periods, and then, 
as directed by the instructor, plot on section-paper 
a curve of your readings. Lay off the observed 
weights as ordinates, the time-intervals as abscis- 
sae. Be sure that in this and all subsequent ex- 
periments your inferences are only those warranted 
by your observations. 
Experiment 2. — To ascertain one cause of loss of weight 
of plants. 

1. Take four clean, dry glass beakers or tumblers, two 
pieces of cardboard large enough amply to cover the 
opening of the beaker, and a vigorous green leaf 
having a leaf-stalk and a perfectly dry surface. 

2. Fill two of the glass beakers or tumblers three- 
fourths full of water, insert the leaf-stalk through 
a small hole in the center of one piece of cardboard, 
make the opening as tight as possible about the 
leaf-stem, using cotton if necessary, and place the 
cardboard over one of the water-containing beak- 
ers, so that the leaf-stalk extends down into the 
water. Invert one of the dry beakers over the leaf. 
Arrange the other two beakers and cardboard in 
the same way, only omitting the leaf and the hole 
through the cardboard. This second set of beak- 
ers is the control {cf. p. 3, 1[6). 

3. Place both sets of beakers in a well-lighted window, 
preferably in direct sunlight, and from time to time 
observe and compare the appearance of the inner 
surfaces of the inverted beakers. 

4. Do you notice any difference in the result on oppo- 
site sides of the leaf? If so, describe. 

5. Can you see any water passing from the leaves? 
In what state, therefore, does it pass off? From 
what part of the leaf does it come? Why do you 



24 



ANATOMY AND PHYSIOLOGY 



think so? What change does it undergo in order 
to become visible on the surface of the beaker? 
In what state does it probably exist in the leaf? 
State one reason why the plant lost weight in 
Experiment i. Was this the only cause of its loss 
of weight? 

6. The above experiments demonstrate the fact of 
transpiration. Give a definition of transpiration. 
B. The Control of Transpiration: 

Experiment 3 . — To see if the epidermis affects the rate 
of transpiration. 

I. Take two sound apples. Remove the skin (epider- 
mis) from one of them, then ascertain accurately 
and record the weight of each, in tabular form, as 
follows : 



Time 


Weight in grams 


Day 


Hour 


Unpared 


Pared 











2. Place the specimens in a convenient place, with free 
access of air, and out of reach of mice. 

3. Record, in a table like the above, three (or more) 
subsequent observations of weight at successive 
class periods. 

4. Plot two curves showing the rate of loss of weight. 
Include these curves and their interpretation as 
part of your record of the experiment. 

Experiment 4. — To demonstrate the effect of the 
*'skin" of a potato-tuber on transpiration. 



TRANSPIRATION 25 

1. Proceed as directed for Experiment 3, using two 
sound potatoes instead of apples. 

2. The "skin" of an apple is a true epidermis, having 
an outer layer of cuticle, which is not readily per- 
meable by water. The "skin" of a potato- tuber 
is more complex, consisting of several layers, one 
of which is a layer of cork-tissue. It is this corky 
layer which chiefly retards the loss or water from 
the tubers. 

Experiment 5. — After noting the color change caused 
by wetting dry cobalt paper (prepared by dipping 
filter paper into a solution of cobalt chloride and 
thoroughly drying it), make the following experi- 
ment: Place discs of the cobalt paper {e.g., as 
large as a five cent piece) on opposite sides of a 
lilac leaf, and hold all in place between two micro- 
scopic slides (or larger pieces of glass), fastened 
with rubber bands around each end. Compare the 
rate of color change of the two opposite discs, and 
infer the cause. 

Other leaves, having structural peculiarities 
similar to those of the lilac, may be used; e.g., 
hibiscus, osage orange, oleander, lizard's tail 
{Saururus) . 

Experiment 6. — Examine, with the microscope, strips 
of both upper and lower epidermis of the leaf used 
in Experiment 5, and infer the probable cause of 
the differential color-change observed. 

Experiment 7. — Place any suitable, well-watered potted 
plant on postal scales, "household" scales, or other 
convenient weighing device, after first carefully 
wrapping the pot in sheet-rubber, or sheet-oil- 
cloth, as in Experiment i. Record the loss of weight 
at fiiteen-minute (or other suitable) intervals while 



26 ANATOMY AND PHYSIOLOGY 

the experiment is standing for an hour, each, in (a) 
direct sunlight and breeze; (b) diffuse sunlight, and 
the comparatively still air of a room; (c) under a 
glass bell-jar, or large box. The breeze may be 
secured by placing the experiment in or near an 
open window or other draught, or by means of an 
electric fan. 

On the basis of your observations in Experiment 7, 
discuss the control of transpiration by external 
conditions, and suggest differences in the condition 
of the plant caused by its exposure in the various 
situations suggested above, and the effect this would 
have on the rate* of transpiration. Were the results 
observed in the three situations strictly comparable? 
Why? 
C. One EJffect of Transpiration: 

Experiment 8. — To show the so-called ' 'lifting power" 
of transpiration. 

1. Insert a leafy stem of a living plant (a branch of any 
evergreen is excellent to use) into one end of a piece 
of glass tubing about 3 ft. long, of small bore, and 
full of tap-water, taking special care to have the 
joint between the stem and the glass air-tight, 
using rubber tubing for this purpose if neces- 
sary. The experiment will be more satisfactory 
if the stem is cut off under water, and the cut 
end kept from contact with air, throughout the 
experiment. 

2. After being sure that the glass tube is full of water, 
place it upright in a dish of mercury, having care 
not to allow any of the water to run out in so doing. 

3. Place the experiment in sunlight, if possible, but 
do not leave it in direct sunUght for more than one- 
half to three-quarters of an hour. 



TRANSPIRATION 27 

4. At the beginning of the experiment, and at suitable 
intervals thereafter, as directed by the instructor, 
measure and record the height of the mercury in 
the glass tube. 

5. Make two drawings of this apparatus in longitudi- 
nal section: (a) as soon as the experiment is set up; 
(b) at the close of your final observation. Label 
all essential parts. 

6. You have made this last experiment with a living 
plant. The question now naturally arises: Is the 
result observed due to the life-factor involved, or 
is it merely the result of some physical condition, 
as, e.g., the evaporation involved? The question 
may be easily answered by setting up an experiment 
similar to the preceding, but using non-living 
material, as follows: 

Experiment 9. — To see if evaporation exerts a ^'lifting 
power." 

1 . Tie a piece of porous animal membrane {e.g., bladder) 
over a thistle-tube, being sure that there is no 
chance for a leak between the glass and the 
membrane. 

2. Fill the this tie- tube with water. 

3. Prepare a dish of mercury and also a clamp to hold 
the tube in place. 

4. Invert the thistle-tube and place the lower end in 
the mercury, being sure that no air enters the tube. 
By this arrangement all factors of Experiment 8 
have been eliminated except evaporation, and the 
evaporation takes place through only one mem- 
brane, and that a non-living one. In other words, 
we have Experiment 8 reduced to its lowest terms. 

5. Observe and record the height of the mercury in the 
tube as in^Experiment 8. 



28 ANATOMY AND PHYSIOLOGY 

6. Make a drawing of this apparatus in longitudinal 
section at the beginning and at the close of the 
experiment, labeling all essential parts. 

7. The conclusions drawn from this experiment should 
cover an explanation of the bearing of these results 
on Experiment 8. 



VI. Absorption of Water by Plants 

A. External Anatomy of the Root: 

1. Examine roots of seedlings (mustard, flax, oats, 
etc.), grown in a moist chamber {e.g, flower-pot, 
or saucer of same), and ,kept covered with a glass 
plate so as to expose them to the air as little as 
possible. Note the delicate white hairs on them. 
Describe their distribution and relative size. These 
hairs are root-hairs. 

2. Hold the root up to the light and note the more 
transparent tissue on the end (root-cap), covering 
the root-tip proper. How is the latter distin- 
guished? Is "root-tip'' synonymous with "end of 
the root?" Explain. 

3. Make a drawing of the seedling, at least twice 
natural size, showing these features. (The labeling 
of the root-cap and root-tip may be deferred until 
observation B, 3, below, has been made.) 

B. Microscopic Characters of the Root: 

1. With the scalpel carefully remove the terminal 
5 to 6 mm. of a root, with the root-hairs, and mount 
it in water. Locate the oldest and youngest root- 
hairs. How are they distinguished? Do they 
branch? What relation do the hairs bear to the epi- 
dermis? Are they divided by cross-walls? Do they 
contain nuclei? What is a root-hair, structurally? 

2. Make a drawing (high power) of three or four hairs, 
showing their structure and relation to the epider- 
mis. The hairs should be drawn at least 50 to 75 
mm. long. 

29 



30 ANATOMY AND PHYSIOLOGY 

3. Distinguish the root- tip from the root-cap. Of 
what is the latter composed? Describe it. Draw. 

C. The Function of Root-hairs: 

1. Carefully pull up a mustard seedling growing in 
sand and having several leaves. Without injuring 
the plant, carefully and very gently shake off all 
sand that readily falls away. Does the sand adhere 
with equal firmness to all portions of the root? 
Describe in detail, explain, and illustrate by a 
drawing, X2. 

2. Pull up another seedling of the same age, and remove 
all or most of the adhering sand. Replant both 
seedlings in sand, water them, and set them aside 
until the next period. In order to eliminate indi- 
vidual dijfferenfes it is necessary to treat several 
seedlings in each of the ways above indicated. 

3. At the next meeting of the class observe and com- 
pare the appearance of the seedlings. In thor- 
oughly removing the sand from the seedlings, how 
were the root-hairs affected? 

4. By means of what organs does a land plant obtain 
most of its water? State, in a paragraph, the 
reasons for your answer. 

5. We have ascertained the organs whose function 
it is to take in water from the soil. It is now 
important to inquire by what process the soil- 
water passes into the plant through the organs 
of absorption. 

D. How the Root-hairs Take in Water; Osmosis: 

I. The preceding studies of the plant cell lead us to 
recognize the fact that the root-hair is an individual, 
elongated cell. Within is the cell-sap, a solution 
of various salts; without, as the plant grows in the 
soil, is the soil- water, also containing numerous sub- 



> ABSORPTION OF WATER BY PLANTS 3 1 

stances in solution. The cell-sap of the root-hairs, 
and the soil water, are solutions of different densi- 
ties, and separated by layers of porous (semiper- 
meable) plant substance. Name these layers. 
Experiment 10. — To see what results when two liquids 
of unequal density are separated by a porous mem- 
brane: 

2. With a pen knife or a pair of scissors, remove a 
portion of the shell from the large end of a hen's 
egg, taking great care not to puncture the mem- 
brane that separates the white of the egg from the 
shell. 

3. Carefully place the egg thus prepared upright in 
a glass tumbler, or beaker, and pour in tap-water 
until the water surface is about i in. above the 

4. By the above arrangement the solution of various 
salts intermingled with the substance of the egg 
serves as the more dense liquid, the water outside 
as the less dense, while the membrane in the egg 
acts as the porous membrane, separating the two 
liquids. In other words, we have roughly imitated 
the plant cell, though there is nothing in the cell 
that corresponds to the shell of the tgg. 

5. Make a careful drawing, showing the experiment 
in longitudinal section, and about one-half natural 
size. Label all parts. 

6. Make an observation at the end of an hour; of 
two hours. Describe what results, and illustrate 
the final result by another sectional drawing 
opposite the first one. 

7. State as clearly as you can what has taken place 
in order to produce the result observed. The 
process is termed osmosis (Greek, osmos, pushing). 



32 AXATOilY AND PHYSIOLOGY 

8. In this experiment, what part of the root-hair 
does the egg membrane represent? the solution of 
salts in the egg? the water in the beaker? 

9. From the above study explain what takes place 
when a root-hair is in moist soil. \Miat is thus 
accomplished for the plant? 

10. Denne osmosis. 

Experiyn-ent 11. — To demonstrate osmosis in a plant 
ceU: 

11. Mount in water several uninjured root-hairs. 
Again identify (high power) the Hning layer of 
cytoplasm. IMake a drawing of one of the root- 
hairs about 50 mm. long. Leave room for two 
other drawings by the side of the first one. Run 
a drop of a 5 per cent, salt solution under the 
cover-glass. This solution is more dense than the 
cell-sap. 

12. Describe the effect of the salt solution on the proto- 
plast. 

13. Make a drawing by the side of the first one, showing 
what you observe. What is the process called? 

14. Xow thoroughly irrigate the cells with fresh water, 
and observe and describe the result. Explain as 
fully as you can. 

15. By the side of your second drawing make a third, 
showing the cell as it appears after irrigation with 
fresh water. 

16. In a sentence, name, in order, two processes that 
take place, (a) when a H\dng plant cell is immersed 
in a solution more dense than the cell-sap; {h) when 
a plasmolyzed cell is irrigated with tap-water. 

17. WTiat is one function of the salts dissolved in cell- 
sap? WTiat is one function of the plasma mem- 
brane? 



ABSORPTION OF WATER BY PLANTS 33 

Experiment 12. — Demonstration of the Osmoscope 
(by the instructor).* 

18. Make a drawing showing clearly all essential parts 
as seen in longitudinal section, and describe the 
apparatus as set up and explained by the instructor. 

19. Record observations on the height of the column 
of water in the tube of the osmoscope: 

{a) At the beginning of the experiment. 
{h) On successive half-hours, 
(c) On successive days. 

20. Explain the results observed. 

Experiment 13. — Demonstration of ''exudation-pres- 
sure" (by the instructor). 

21. Describe and make a drawing of the experiment at 
its beginning, as set up by the instructor. 

22. Complete your observations and record as directed 
under Experiment 12, naming the species of plant 
used. 

23. Compare the conditions and results in this experi- 
ment with those in Experiment 12. 

*It is here taken for granted that the instructor will be able to 
make this demonstration (as well as that under Experiment 13) without 
further suggestions, using any one of the various types of osmoscope 
commonly found in botanical laboratories. 



VII. The Path of Water in the Plant 

Experiment 14. — To see if there are definite channels 
for the passage of liquids through a stem. 

1. Place the cut ends of various living, leafy shoots 
{e.g., corn, plantain, lily leaves, parsnip, or seed- 
lings of castor-oil plants) , into a solution of f uchsin 
or of eosin, and, after they have stood for a suitable 
time, as determined by the instructor, observe 
freshly exposed end- surfaces, and note the regions 
where the colored solution appears. Does it pass 
up through the whole mass of tissue, or are there def- 
inite channels through which it rises? Cut sections 
of the stems at various heights, and observe and 
describe the distribution of the colored areas. 

2. Compare the distribution of the colored areas in a 
parsnip (or seedling of a castor-oil plant) and a 
stalk of corn (or petiole of some lily leaf). Make 
a diagram to illustrate this. 

3. Examine the end of a dry com stalk, and note the 
projecting strands. What relation do they bear to 
the paths of the eosin? They are composed of 
fibers and vessels united, and are therefore called 
fibro-vasciilar bundles. 

4. Carefully cut the epidermis in a ring around the 
petiole of a leaf of plantain, being specially careful 
not to cut clear through the petiole. 

5. Taking the end of the petiole in one hand and the 
leaf-blade in the other, gently pull the two portions 
of the petiole a short distance apart. Describe and 

34 



THE PATH OF WATER IN THE PLANT 35 

illustrate by a drawing what you observe. What 
structures are thus disclosed? 

6. What relation do the fibro- vascular bundles bear 
to the veins of the leaf? To the root-hairs? 

7. Write a clear statement of how the water passes 
from the soil into the roots of a plant, and into and 
through the leaves and out into the air, mentioning, 
in order, all parts and processes studied. 



Vlil. Mechanical Uses oj Water in the Plan-t 

A. Rigidity and Maintenance of Form: 

Experiment 15. — To ascertain the cause of rigidity in 
beet tissue: 

1. From a beet cut four slices about 5 mm. thick, 
10 mm. wide, and 75 mm. long. 

2. Place the slices as follows: 
{a) In tap- water. 

{h) In a 10 per cent, salt solution. 
(c) and (J) In boiling water for two or three min- 
utes. 
Then place 
{c) In- tap water,, and 
{d) In the 10 per cent, salt solution. 

3. At the end of fifteen minutes obser\'e and record 
the relative rigidity of the various slices, ascer- 
tained by carefxilly bending them. 

4. Thoroughly rinse the sHces, h and d, and then 
transfer them to tap-water. At the end of an 
hour (or sooner) observe them again and describe 
the result. 

5. Explain your observations on the basis of your 
previous experiments. 

6. What is one mechanical use of water in a plant 
tissue, and how is this accomplished? 

Experiment 16. — To demonstrate longitudinal tissue- 
tension. 

7. Obtain a petiole of rhubarb, or burdock, or a 
stalk of celery. With a scalpel make a lengthwise 

36 



MECHANICAL USES OF WATER IN THE PLANT 37 

cut for a distance of about 25 mm. from the end, 
and just beneath the surface. 

8. Describe the position assumed by the severed piece. 
Illustrate by a diagram, natural size. 

9. From another petiole cut off a portion at least 
15 cm. long, with the cut surfaces normal to the 
edges. Record the exact length of the piece in 
millimeters. 

10. With a scalpel carefully remove a thin strip of 
outer tissue along the entire length of the piece 
(or remove a strip of "bark" from a very young 
woody stem). At once try to replace it. Has it 
altered in length? If so, describe. Make another 
similar observation at the end of ten or fifteen 
minutes. What would you have to do to the 
strip to make it resume its former length? 

11. Carefully measure the length of the excised strip 
about fifteen minutes after its removal. Record 

[ this measure, and calculate the percentage of change 
' in length. 

12. From another portion of the petiole cut off two 
strips from opposite sides (or the bark from a 
portion of some young woody stem). Place one 
of the excised strips in water, another in a 10 
per cent, salt solution. 

13. At the end of five or ten minutes compare the 
lengths of the two strips, (a) with each other, 
ijb) with the portion of the stem from which they 
were cut. Explain what you observe. 

14. From the preceding studies describe the condition 
of the tissues in a plant stem. To what is this 

/condition due? 

15. Of what advantage do you think this condition 
would be to the plant? 



38 ANATOMY AND PHYSIOLOGY 

Experiment 17. — To demonstrate transverse tissue- 
tension. 

16. Take short portions (about 15 or 20 mm. long) 
of some woody stem 15 to 20 mm. in diameter, 
and with the scalpel make a clean cut lengthwise 
through the bark, and remove the bark, being 
careful not to crack or break it. 

17. At once, or at the end of four or five minutes, 
try to replace the bark. Describe your success 
in so doing. Draw, end view and side view. 

18. What must be done to the bark in order to restore 
its original length? 

19. From this study what further do you know of the 
condition of the tissues in a plant stem? Explain. 



IX. Nutrition 

A. The nutrition of plants is very similar to that of 
animals, with the exception that all green plants 
manufacture their food out of inorganic chemical com- 
pounds. Animals cannot do this. They must conse- 
quently receive their food ready-made. But there are 
some lower organisms (doubtfully animals) that pos- 
sess the ability to elaborate their food out of inorganic 
compounds, while on the other hand, certain plants, 
such, for example, as the mushrooms and other plants 
wanting chlorophyll, lack this power. 

B. The manufacture of carbohydrates is, in many respects, 
the most important function of green plants. With- 
out it life would be impossible, so that its study 
becomes of very great interest. We will first learn 
how to detect the presence of a carbohydrate such as 
starch, then study its occurrence in plants, and finally 
the process by which it is made out of simpler chemical 
compounds. 



39 



X. The Occurrence or Carbohydrates in Plants 

A . The Test for Starch: 

Experiment i8. — To ascertain the test for the presence 
of starch. 

1. Place a bit of corn starch, about the size of a small 
shot, into a test-tube one-fourth full of water. 
Shake it thoroughly. Is starch soluble in cold 
water? Give a reason for your answer? 

2. Bring the starch mixture to a boil over the flame 
of an alcohol lamp, or Bunsen burner. Describe 
the result. Is starch soluble in hot water? Give 
a reason for your answer. 

3. Set this test-tube aside to cool for a moment or 
two. 

4. Into a test-tube one-fourth full of clear water 
place 3 or 4 drops of iodine solution, using a pipette. 
Shake the mixture and describe the color. 

5. Now place i or 2 drops of the iodine into the 
cooled, boiled starch mixture. Shake the mixture 
and describe the resulting color. 

6. Pour one-half of this mixture into another test-tube 
one-half full of water. ^Miat color appears? 

7. Describe a test for the presence of starch. (Note: 
The iodine is not the test; it is only the reagent 
used.) 

Experiment 19. — To see if there is starch in (j) seeds; 
{b) stems; {c) roots. 

40 



OCCURRENCE OF CARBOHYDRATES IN PLANTS 4 1 

8. Boil in water, in a test-tube, portions of the above- 
mentioned parts of plants, and proceed with the 
starch test, as above outlined. Record the experi- 
ment as usual. Be careful to distinguish between 
your observations and your inferences. 

Experiment 20. — Microchemical tests for starch. 

9. If time permits of individual tests by the student, 
microchemical tests may be made by mounting in 
water, on microscopic sHdes, small portions of, 
first, commercial starch; second, material scraped 
from any soaked seeds {e.g., corn, bean), a potato- 
tuber (a stem), any convenient fleshy root, in each 
case observing (and drawing) the shape, surface- 
markings, and characteristic groupings of the starch 
grains, then running under the cover-glass a drop 
of iodine solution, and observing the color reaction. 

Experiment 21. — To see if there is starch in leaves. 

10. Extract the chlorophyll from leaves of nasturtium, 
bean seedling, or other convenient large-leaved 
plant, by placing the leaf first in hot water to facili- 
tate the extraction; second, in hot alcohol, or, after 
they have been dipped in hot water, the leaves may 
be left in cold 80 per cent, alcohol until the following 
class period. 

11. Describe the effect of the alcohol on the color of the 
leaf, and state your inferences as to the solubility 
of chlorophyll. 

12. Place the leaf in a watch-glass, and irrigate it 
with iodine solution. After a few moments pour 
off the iodine, and observe the color of the leaf. 
This last observation is often made more striking 
by placing the leaf on a small piece of glass, and 
holding it to the light. State your inferences from 
this observation. 



42 ANATOMY AND PHYSIOLOGY 

13. If preferred, de-chlorophyllized leaves may be cut 
into small pieces, boiled in water in a test-tube over 
a Bunsen flame, and the water then tested for the 
presence of starch. 
B. Test for Sugar: 

1. We have seen that starch is a practically insoluble 
carbohydrate. We also know that sugar is a read- 
ily soluble carbohydrate. The chemical formula for 
a molecule of starch is CeHioOs. If we combine 
with this molecule one molecule of water (H2O) we 
have a molecule whose composition is represented 
by the formula CeHiaOe L(C6Hio05)n + H2O = 
C6H12O6]. Tins is grape sugar. Sugar, then, differs 
from starch in possessing relatively more hydrogen 
and oxygen in its molecule. The process of con- 
verting starch into sugar is termed hydrolysis, and 
since it converts an insoluble substance into a 
solubile one, it is a kind of digestion. 

2. The sugar ordinarily used for cuKnary purposes is 
cane sugar. Its formula is C12H22O11. Explain 
how cane sugar differs from starch chemically. 

Experiment 22. — To demonstrate a test for the presence 
of grape sugar (C6H12O6). 

3. The reagent commonly used for this test is called 
Fehling's solution, from the name of the scientist 
who first employed it. The solution is prepared 
by mixing one volume of each of the following stock 
solutions with two volumes of distilled water {e.g., 
10 c.c. of each, and 20 c.c. of distilled water). 

(i) 1 7. 5 grams of copper s\ilphate dissolved in 5 00 c.c. 

of distilled water. 
(2) 86.5 grams of sodium-potassium- tartrate (Ro- 

chelle salts) in 500 c.c. of distilled water. 



OCCURRENCE OF CARBOHYDRATES IN PLANTS 43 

(3) 60 grams of sodium hydrate in 500 c.c. of dis- 
tilled water. 

The mixture, properly made, has a dear blue 
color. 
If the Fehling's solution is not freshly prepared, 
it should be tested, before using, by heating a por- 
tion in a test-tube until it boils. If a precipitate 
of red copper oxide does not form the solution is 
good. It is better to make this test even with fresh 
solution. 

4. Place a very small amount of grape sugar into a test- 
tube one-third full of water. 

5. Shake the solution and gently warm it, then add a 
few drops of Fehling's solution. 

6. Describe what results. The effect is due to the 
grape sugar reducing (i.e., taking oxygen from) 
Fehling's solution, forming cuprous oxide. 

7. State the test for grape sugar. 

Experiment 23. — To demonstrate a test for the 
presence of cane sugar. 

8. Proceed as in the preceding experiment, using cane 
sugar instead of grape sugar. Observe and describe 
the result. 

9. Prepare a second test-tube with a solution of cane 
sugar. 

10. Add several drops of hydrochloric acid, and boil the 
mixture. 

11. Now add several drops of Fehling's solution (enough 
to neutralize the acid). 

12. State the test for cane sugar. 

Experiment 24. — To demonstrate the occurrence of 
sugar in plant tissues. 

13. Test portions of onion, beet, sweet corn, sweet 



44 ANATOMT AND FHYSIQLOGY 

potato^ etc., for sugar. Describe the result in each 
case. 
14. Write a brief samniaiy of what you have learned 
concerning the occurrence and distribuUon of carbo- 
hydrates in plants. 



XI. Formation of Carbohydrates 

A . The Conditions Necessary for Carbohydrate Formation: 
Experiment 25. — To ascertain if light is necessary for 

carbohydrate formation. 

1. A green leaf, previously partly shaded by having a 
strip of black cloth closely affixed to both sides, is 
to be tested for starch as described under Experi- 
ment 21, after having been in the sunlight for several 
hours. Record as previously directed.* 

Experiment 26. — Is chlorophyll necessary for carbo- 
hydrate formation? 

2. As directed under Experiment 21, test a variegated 
leaf, having white areas devoid of chlorophyll. 
Make three drawings of the leaf, as follows: {a) 
showing (by shading) the distribution of chloro- 
phyll in the tissues; {h) showing the leaf decolorized; 
ic) showing (by shading) the areas that gave the 
starch reaction with iodine. 

B. Effects of Light on Chlorophyll: 

Experiment 27. — To show the need of sunlight for the 
formation of chlorophyll by chloroplasts. 

1. Examine a seedling of any convenient plant that 
has been allowed to develop in darkness. Compare 
its color with that of another seedling of the same 
species grown in dayUght. 

2. Now place the seedHng in diffuse sunHght for 
twenty-four to forty-eight hours. Record the re- 
sult, and state your inferences. 

*The "light screen," devised by Professor Ganong, for experiments in 
starch formation by leaves, is specially recommended for this experiment, 

45 



46 ANATOMY AISTD PHYSIOLOGY 

C. The Exchange of Gases in Photosynthesis: 

Experiment 28. — To demonstrate the evolution of gas 
in photosynthesis. 

1. Observe uninjured branches of Elodea growing in 
water in direct sunlight. (For individual experi- 
ments one or two branches in a large test-tube of 
tap-water will serve.) Describe what you observe, 
coming from the basal ends, or other parts of the 
stems. 

2. Shade the plants for a moment by interposing a 
note-book or other convenient screen between them 
and the sun. Describe how the process just ob- 
served is affected. 

3. Make a diagram of the apparatus and material, 
showing what you have observed. 

4. Observe the bubbles among a mass of any green 
alga floating in water, and explain their presence. 

Experiment 29. — To demonstrate what gas is given ofi 
in photosynthesis. 

5. With a rubber band, or other convenient means, 
fasten together (not too tightly) the cut ends of 10 
or 15 clean branches of Elodea, and place them into 
a glass funnel, with the cut ends extending upward. 
Invert the funnel into a jar of water. The surface 
of the water should rise an inch or two above the 
neck of the funnel. 

6. Fill a test-tube with water and invert it over the 
neck of the funnel, being careful that no air enters 
the tube. 

7. Place the apparatus in bright sunlight, and when 
sufficient gas has been collected in the test-tube, 
test it with a glowing splinter. How is the splinter 
affected by the gas? What gas does this test indi- 
cate? The best success of this experiment requires 



V FORMATION OF CARBOHYDRATES 47 

that the gas be tested the same day that the experi- 
ment is set up. Especially avoid setting up the ex- 
periment in the afternoon and testing the gas on the 
following morning. Why? 
Experiment 30. — To demonstrate what gas is taken 
into the plant in photosynthesis. 

8. Into each of three large glass evaporating dishes, 
A, B, and C, place a glass bell- jar having a wide, 
open tubulature at the top. Into two of the bell- 
jars, A and B, place vigorous, green-leaved shoots. 
Into C place no shoot. Under each bell-jar place 
a piece of hghted candle, 2-3 in. high, supported 
on a flat cork. Now pour water into the evap- 
orating dishes until it rises 2 or 3 in. up the side 
of the bell-jars. The burning of the candles shows 
that there is enough oxygen in the jars to support 
combustion. 

9. Now cork the bell-jars air-tight with rubber stop- 
pers. What soon results to the candle flames? 
What does this tell you of the amount of oxygen 
now in the jars? 

10. Cover the jar B, containing a shoot, with opaque, 
black cloth, and set all three preparations in sun- 
Hght. 

11. State, in a well- worded paragraph, the condition in 
each bell-jar as to light, chlorophyll, and the com- 
position of the air. 

12. At the end of two or three hours, carefully lower 
into each jar, successively, a lighted candle attached 
to the end of a long wire. Record your observation 
and inference for each jar, and your final inference 
as to what gas is taken into the plant in photosyn- 

' thesis, and what conditions are necessary to the 
process. 



Xir. The Digestion of Starch: Tilanslocatiox 

A. Tlie Sturch-cantent of Leaves During the Day and at 
Night:^ 

Experiment 31. — To find out if starch is present in 
leaves gathered in darkness as well as in light. 

1. Dechlorophyllized leaves of clover (or of one of the 
first five plants listed in the table in the foot-note 
below), collected (a) in bright sunlight, (b) several 
hours after sunset, will be tested by the instructor 
for the presence of starch. 

2. Did both leaves probably contain starch during 
the day? From this experiment what do you 
know has taken place in the leaf gathered at night? 
Is starch soluble? WTiat, then, must have occurred 
to the starch? 

^Miss EcKERSON (Bot. Gaz., 48: 224-22S. S1909) recommends the 

following plants for this study, since in them photos}Ti thesis is ver>' ac- 
tive, starch disappears from their leaves in darkness with comparative 
rapidity, chlorophyll is easily extracted, and the iodine reacts quickly: 



Name of Plant 



Disappearance 

of starch in 

darkness 

(T. i8°-22°C.) 



Formation of starch in 
light (T. 20='-25 = C.) 



Perceptible 
fig. 



Good fig. 



Iodine 
test 



Xights days Minutes Minutes Minutes 



Cticurhita Pepo 







15 


50 


4-1 5 


HeJi-anthus annuus 







30 


120 


5 


Impatiens SuUani 







30 


120 


5 


Phaseoliis vulgaris 







20 


90 


5 


Rkinus communis. . . .•. 







20 


60 


S-15 


TropcBvlum m<jjus 


2 


I 


SO 


90 


I 


Zea Mais 


3 


2 


30 


120 


5 







48 



<. THE DIGESTION OF STARCH 49 

3. Name two advantages to the plant of this new 
process you have studied. 

4. The changing of an insoluble substance to a soluble 
one and dissolving it is digestion. 

5. Briefly enumerate, in order, using the proper 
scientific terms, the processes that you have learned 
take place in a green leaf from sunrise to sunrise 
again. 

B. Conversion of Starch to Sugar: 

Experiment 32. — To see if starch may be digested 
to sugar by an enzyme. 

1. Into a test-tube one-half full of a dilute starch 
mixture place several drops of iodine. 

2. Add to this mixture a few drops of a solution of 
diastase. 

3. At intervals of fifteen to twenty minutes test for 
sugar. Describe all color changes observed through- 
out the experiment. 

C. State with special care and detail the inferences warranted 
by experiments 31 and 32.^ 

^ Note : The study of proteins and fats is here omitted, not being con- 
sidered essential in an introductory course. 



XIII. Alcoholic Fermentation 

A. The development of heat by alcoholic fermentation: 

1. In these experiments fresh compressed yeast may- 
be used, and, for a fermenting substance, either 
commercial molasses (20 ex.) in water (100 c.c), 
or Pasteur's solution, made up as follows: 

Pasteur^s Fermentation Solution 

Grape sugar 150 c.c. 

Ammonium tartrate 10 c.c. 

Magnesium sulphate 2 grams 

Calcium phosphate 2 grams 

Potassium phosphate 2 grams 

Distilled water 838 c.c. 

Experiment 7,^. — To ascertain what temperature change 
accompanies alcoholic fermentation. 

2. Place about 5 grams of compressed yeast in 250 
c.c. of the Pasteur's solution, shake well, and pour 
into a Dewar flask. 

3. Place a similar amount of distilled (or tap) water 
in a second flask. 

4. Record the temperatures of both liquids at once, 
using two thermometers which should remain in 
the Hquids until the experiment is over.^ The 
experiment will work best if the liquids are at 
about 25°C. 

^ The instructor will, of course, understand the necessity of carefully 
comparing the initial readings of the thermometers, where two or more are 
used, and of making necessary corrections in subsequent readings. 

SO 



% ALCOHOLIC FERMENTATION 5 1 

5. Set the two Dewar flasks side by side where they 
will not be subject to great or unequal changes 
of external temperature. 

6. At frequent intervals {e.g., twenty minutes) during 
the next two hours, record the temperatures of 
the two fluids. Continue the records over as long 
a period as convenient, not exceeding twenty-four 
hours. 

7. Tabulate the results, and from the figures con- 
struct two ''curves," showing the rate and amount 
of temperature change in each flask. 

8. State your inferences from this experiment. 
B. The gaseous exchange in alcoholic fermentation: 

Experiment 34. — To ascertain what gaseous exchange 
accompanies alcoholic fermentation. 

1. Place 250 c.c. of fermenting mixture into a tall 
glass cylinder, and 250 c.c. of distilled water into 
a similar adjacent cylinder, as a control. At 
once test the air in the cylinders above the liquid 
with lime water, to see if the latter turns milky, 
as a result of the formation of a precipitate of 
carbonate of lime.^ 

2. After the test for CO2, test the air in both cylinders 
with a lighted splinter or taper, to see if it contains 
suflScient oxygen to support combustion. The 
taper should be rapidly lowered into and removed 
from the cyHnder. Why? 

^ If the members of the class are not familiar with the effect of COj on 
lime water, this should be demonstrated by the instructor, using both 
chemically prepared CO 2 and the breath from the lungs, before proceeding 
with the experiments in fermentation and respiration. 

The air in the cylinder may conveniently be tested by first dipping a 
small wire loop {e.g.y 10 mm. in diameter) into lime water. A film of the 
lime water will form across the loop, and may thus be transferred into the 
cylinder. 



52 ANATOMY AND PHYSIOLOGY 

3. Place a greased glass plate over each cylinder, or 
close the cylinders with a rubber stopper, and after 
an interval of about one hour (at a temperature 
of about 25°C.) repeat the tests for O and CO2. 
Test again after two or more hours. 

4. Record and interpret your results, especially dis- 
cussing any circumstances that may have operated 
to affect the progress of the experiment either favor- 
ably or unfavorably. 

C. The Formation of Alcohol Demonstrated: 

Experiment 35. — To test for the presence of alcohol. 

1. After the fermentation in the last experiment has 
proceeded for twenty-four hours, distill about 150 
to 200 c.c. of the fermenting liquid, and redistill the 
first distillate. 

2. Test a portion of the second distillate with a flame 
to see if it will burn. If it will, describe and explain 
the result. 

3. The presence of alcohol may also be tested, in 
either the first or the second distillate, by adding to 
it several drops of a mixture composed of a strong 
aqueous solution of bichromate of potash, to which 
have been added a few drops of sulphuric acid. If 
a green color results, the presence of alcohol is 
indicated. 

4. Briefly summarize the products of alcoholic fer- 
mentation, ascertained by the above experiments. 
From where did these products come, and what 
was the active agent in their formation? 



XIV. Respiration 

A. Anaerobic Respiration: 

Experiment 36. — To illustrate anaerobic respiration. 

1. Remove the seed-coats from three or four pea seeds 
that have soaked in water over night. 

2. Fill a large glass test-tube with mercury, and 
invert it in a bath of mercury. 

3. Place the pea seeds under the mouth of the inverted 
test-tube, and allow them to float to the top. Use 
every possible precaution to prevent air being car- 
ried up with the peas. Can the presence of air 
be entirely prevented? 

4. Securely fasten the test-tube in the inverted posi- 
tion, with its mouth under the surface of the mer- 
cury in the bath, and during the next twenty-four 
to forty-eight hours observe the formation of 
gas, which replaces the mercury around the seeds. 

5. Now introduce into the test-tube with the pea seeds 
a small piece of potassium hydroxide. If the gas 
given off by the seeds is CO2 it will be absorbed by 
the potassium hydroxide, and the mercury will rise 
in the tube. 

6. Do these seeds respire under strictly anaerobic con- 
ditions? Discuss, iny our note-book, all the pros 
and cons, and endeavor to make a clear statement 
of just what this Experiment does and does not 
demonstrate. 

B. Aerobic Respiration: 

Experiment 37. — To demonstrate what exchange of 
gases accompanies the aerobic respiration of a living 
plant. 

S3 



54 ANATOMY AND PHYSIOLOGY 

1. Place a \dgorous potted plant on a ground-glass 
plate. By the side of it place a watch-glass full of 
lime water, or baryta water; over all place a glass 
bell-jar with a large tubulature at the top. 

2. Make the joint between the bell-jar and the ground- 
glass plate air-tight by means of vasehne. 

3. Test the air in the jar with a lighted taper to be sure 
that it contains enough oxygen to support combus- 
tion. 

4. Insert a rubber stopper into the tubulature so as 
to make it air-tight, and set the plant aside, in a 
dark place. Why? 

5. At the next laboratory period (preferably on the 
following day), and without disturbing the bell-jar, 
observe the color of the lime water in the watch- 
glass. What does it indicate? 

6. Quickly and cautiously insert a hghted taper into 
the bell-jar through the tubulature. What results? 
What inference is justified? 

Experiment t,^. — To see if all parts of a plant, and non- 
green plants, respire. 

7. Take six cylindrical glass jars, a, b, c, d, e, and /, 
provided with air-tight rubber stoppers. 

8. Into (a) place a quantity of green leaves; into (6) 
green stems of some herb; into (c) young clean 
roots of some herb; into (d) freshly picked flowers; 
into (e) one or two fresh fleshy fungi; and into (/") 
nothing. Confine the plant material to one side 
of the jars by inserting a vertical partition of coarse 
wire netting. 

9. Test the air in each jar to be sure that it will sup- 
port combustion, then cork the jars air-tight, and 
place them in a convenient place. 

10. At the next laboratory period carefully test the air 



RESPIRATION 55 

in each jar with the burning taper. What infer- 
ence may be drawn from the result? 

11. Next, pour into each jar a bit of clear lime water, 
and wash the air by tipping the jars back and forth, 
holding the half containing the plant material upper- 
most. What conclusion does the result justify? 

12. Clearly state the general conclusion from this ex- 
periment. 

C. The Temperature Change Accompanying Plant Res- 
piration : 

Experiment 39. — To ascertain what temperature change 
accompanies the respiration of germinating seeds. 

1. Place a quantity of germinating seeds {e.g., oats, 
wheat, lupine) into a Dewar flask. Into a second 
Dewar flask place nothing. 

2. Into each flask insert a thermometer (being sure 
fi,rst to compare their readings). The bulb of the 
thermometer in the flask containing the seeds 
should be well covered by them. Place the flasks 
where they will not be subject to great nor unequal 
changes of external temperature. 

3. After twenty-four hours record the temperature 
indicated by each thermometer. 

4. Thoughtfully discuss and interpret the results ob- 
served. 

5. Compare the process of fermentation with that of 
respiration. What inference is suggested by this 
comparison as to the real nature of respiration? 



XV. The Intluence of External Conditions on the 

Plant 

A . The Influence of Gravity o-n the Direction of Growth : 
Experiment 40. — To find how gravity affects the direc- 
tion of growth of roots and shoots. 

1. Choose two or three young seedlings of the pumpkin 
or lupine, with radicles about ro mm. long. 

2. Pin the seedlings horizontally on a cork and place 
in a moist chamber in the dark (why in the dark?) 
until the next period. A Petri dish will furnish a 
simple moist chamber. 

3. Make a drawing of the seedlings in the horizontal 
position. 

4. At the next laboratory period observe the position 
of both root and shoot. Draw. 

5. Do the results give any e\'idence that the root grew 
downward and was not pulled down by gravity? 
Explain. 

B. Influence of Light on the Rate of Growth of Stems: 

1. Compare the lengths of the stems of seedlings of the 
same age that have grown, one in the dark, the other 
in the Hght. State the exact length of each of the 
stems in centimeters. 

2. WTiat do you infer is the effect of Hght on the rate 
of growth of stems of the plants ohseroed? 

3. Do you think this is true of all plants? (This point 
.should be discussed with the instructor, in the light 
of more recent investigations on the subject. See 
especially, MacDougal, ''The Effects of Light and 

S6 



INFLUENCE OF EXTERNAL CONDITIONS ON THE PLANT 57 

Darkness on Growth and Development.^^ Memoirs 
of the New York Botanical Garden, No, 3.) 
C The Influence of Light on the Direction of Growth of Roots 

and Stems: 

Experiment 41. — To ascertain how one-sided illumina- 
tion affects the direction of growth of roots and 
stems. 

1. Fix a vigorous young seedling of white mustard 
with the root extending through the mesh of a piece 
of cheese-cloth stretched over the mouth of a large 
salt-mouthed bottle nearly filled with tap-water. 
The seedling should be as straight as possible, and 
stand vertically at the beginning of the experiment, 
with root extending well into the water. 

2. Place the plant thus prepared into a box with a 
tightly fitting cover and a narrow, vertical slit at 
one side to admit the light. (A pasteboard shoe- 
box with the cover on, and the sHt cut vertically 
in the cover will answer.) 

3. Set the box and plant in a well-lighted window, 
with the slit toward the light. 

4. Make a diagram of the entire apparatus and plant, 
in longitudinal section. 

5. At the next laboratory period carefully remove the 
cover from the box and observe the position of the 
root and stem. 

6. Draw another diagram similar to, and by the side 
of the first one, showing what you observe. 

7. Compare the manner of response of the root and 
stem to one-sided illumination. 



PART II 
MORPHOLOGY AND LIFE HISTORY 



I. Meaning of the Terms 

A. Morphology. — Under Part I we considered various 
physiological processes, the primary result of which was 
to maintain the life of the individual plant. Most of 
those processes were found to be carried on by all 
plants. It is common knowledge, however, that plants 
differ widely from each other in both structure and 
habit of life. In other words, we recognize the fact of 
variation. This means that dij6ferent plants solve the 
same problems of life in different ways. That phase of 
botany which concerns itself with a comparative study 
of structures, and seeks to interpret the structural value 
of an organ, no matter how it may be disguised, is 
termed the science of form, or morphology. 

B. Life History. — Every plant, in the course of its exist- 
ence, passes through a series of changes, in orderly 
sequence. Like an animal, every plant begins Kfe as 
a single cell, the egg, or the equivalent of an egg; 
the egg (except in some of the lower plants) develops 
into an emb3rro, and the embryo grows and develops 
into an adult. The adult in turn, produces an egg, 
like the one from which it came, thus completing one 
life cycle and initiating another. These various 
changes constitute the life history of the individual. 

59 



6o MORPHOLOGY AND LIFE HISTORY 

C. Descent. — Just as one of the higher plants, such as a 
maple tree, begins life as a single cell, and becomes 
more and more complex as it matures, so the plant 
kingdom as a whole, presents us v^ith a series of organ- 
isms of gradually increasing complexity from the sim- 
plest one-celled forms to m\Tiad-celled. complex forms. 
This fact suggests that the entire plant kingdom, like 
every indi\-idual plant, has had a developmental his- 
tor}^, the more complex organisms being derived jro?n 
more simple ones by a series of gradual changes. This is 
the theory of descent, or organic evolution. It teaches 
us that all organisms are related to each other, and 
is one explanation of why we so often find the same 
organ appearing again and again, under various guises, 
in plants externally unhke. 

D. Classification. — The study of morpholog}' and life 
histories enables us to recognize relationships among 
plants, and hence to build up a genealogical tree, 
showing lines of descent. Thus we can arrange plants, 
together with their nearest relatives, in groups; and 
related groups, again, in larger groups of successively 
higher orders. This gives us a rational basis for the 
classihcation of plants, and this phase of plant study 
is called systematic botany, for it makes possible 
the arrangement of plants into a system, zihich en- 
deaz'ors to sho'j, Jwn the plant kingdom, in all its diversity^ 
has developed, or cjohed. This greatly simphnes our 
study of plants, for the number of different plants is too 
great for us to study every one; but if we recognize 
that each plant more or less imperfectly illustrates 
a group, then we can study an illustration of each 
group, and thus get a more nearly adequate picture 
of the kingdom of plants as a whole. The various 
systematic groups are given in E below. 



MEANING OF THE TERMS 



6l 



E. An Outline of the Classification of Plants:^ 
The Great Groups of Plants 



Dirision 


Subdivision 


I 




A. AlgBB ■' 


2 

3 

I 
2 


I. Thallophyta... 




3 




B. Fungi. . . . ■ 

1 


4 
5 
6 



Class 

Cyanophyceffi 

Chlorophycea 

Phaeophyceae 

Rhodophyceffl 

Myxomycetes 

Schizomycetes 

(Bacteria) 
Phycom ycetes 
Ascomycetes 
B asidiom ycetes 
Fungi imperfecti 

(life histories 

imperfectly known) 



Order 



I. Hepaticae. 



II. Bryophyta < 



2. Musci. 



I. Eusporangiatffi. 



III. Pteridophyta. 



IV. Calamophyta. 



V. Lepidophyta. 



VI. Cycadophyta. 



2. Leptosporangiatse. . 

1. Sphenophyllineae. . . 

2. Equisetineae 

3. Calamarineae 

1. Lycopodineae 

2. Lepidodendrineae... 

1. Cycadofilicineae. . . . 

2. Cycadineae. .'. 

3. Bennettitineae 



4. Cordaitinese. 



Ricciales 
Marchantiales 
Jungermannialee 
Anthocerotales 

Andreales 

Sphagnales 

Bryales 

Ophioglossales 

Marratiales 

Isoetales 

Filicales 

Marsiliales 

Sphenophyllales 

Equisetales 

Calamarales 

Lycopodiales 
Selaginellales 
Lepidodendrales 

Cycadofilicales 

Cycadales 

Bennettitales 

Cordaitales 

Ginkgoales 

Gnetales 



^ For reference, not memorizing. 



62 



MORPHOLOGY AND LIFE HISTORY 



The Great Group of Plants — {Continued) 



Division 



VII. Spermatophyta 



Subdivision 

A. Gymno- 
speimse 



B. Angio- 
spermae 



Class 



Order 



--. ., J Coniferales 

^'^'^^'^^^ < Taxales 

Pandanales 

Naidales 

Graminales 

Arales 

Xyridales 

Liliales 

Scitamnales 

Orchidales 

2. Dicotyledoneae 32 Orders, including 

Salicales 



I. Monocotyledoneae 



(fl) Archichlamydeae 
Apetals 
Polypetalae 



(ft) Metachlamydeae 



Polygonales 

Ranunculales 

Resales 

Violales 

Myrtales 

Umbellales 

Ericales 

Polemoniales 



Sympetalse (= \ Plantaginales 



Gamopetal£e) 



Rubiales 
Campanulales 



2. Directions for Study 

Polypodium vulgare (Common polypody) 

A. Classificaiio7i: 

Division III. Pteridophyta (fern plants). 
Class I. Leptosporangiatae. 
Order. Filicales. 

Family. Polypodiaceae. 
Genus. Polypodium, 
Species, vulgare. 

B. Habitat: 

I. Record here your knowledge of the habitat of the 
specimen studied. The information is to be ob- 
tained from your own observation, and from your 
reading and class work. 

The "Fern Plant*' 

C. Naked-eye Characters: 

1. General features. 

{a) Note that the sporophyte is differentiated 
into root and shoot. 

{h) The leaf portion of the shoot is often called the 
frond. The fibrous roots and the leaves are 
borne on an underground stem (rhizome). 

{c) Make a sketch of the entire sporophyte (in- 
cluding only one leaf). 

2. The rhizome. 

(a) Describe the natural attitude {i.e., erect, or 
horizontal) of the rhizome. Where does it 
63 



64 MORPHOLOGY AND LITE HISTORY 

grow? If it branches, describe its manner 
of branching. 

(b) Does the rhizome bear any outgrowths besides 
the leaves and roots? If so, describe their 
structure, color, relative number, and location. 

(c) The places on the rhizome where the leaves are 
borne are called nodes. Wliat is the region 
between two nodes called? 

Note. — The directions below (d-i) apply especially to 
the bracken fern, Pteris aquilina. 

(d) Observe the end of a rhizome cut squarely 
across. If preserved material is used, the cut 
surface should be kept moistened during the 
study. The observations may best be made 
from a piece 5 to lo mm. thick, cut transversely 
and placed in a watch-glass of water. Do not 
cut or injure you specimen in any way, as it 
will be collected for further preser\'ation at the 
end of the study. 

{e) Distinguish the following tissue-regions: 

(i) The epidermis (black in preserved material) . 

(2) Underneath the epidermis a narrow, dark- 
colored region of hypodermal sclerenchyma. 

(3) Within the h}'podermal sclerench\Tna the 
fundamental tissue (parenchjrma) . 

(4) Imbedded in the parenchyma two promi- 
nent elongate, dark-colored areas, the central 
sclerench\Tna, orstereome (sometimes fused 
into one). 

(5) Also imbedded in the parench\Tna, and sur- 
rounding the inner sclerenchyma, several 
areas of fibro-vasciilar bvindles. In fresh 
specimens these areas are yellowish, in 
preserved material they are lighter colored 



DIRECTIONS FOR STUDY 65 

than the inner sclerenchyma. How do 
they appear when a section is held to the 
light? 

(/) Identify all the areas referred to above (e, 1-5) 
in a longitudinal section of the rhizome. 

(g) At home, write a well-worded description of 
your observations under e and/. 

(h) Make a diagram, 10 cm. in longest dianeter, 
showing carefully the outline of the rhizome as 
seen in cross-section, and all the tissue-regions 
identified. Label each region, and underneath 
your drawing indicate the amount of enlarge- 
ment. 

(i) Underneath the first diagram make a second 
one, of the same enlargement, showing the rela- 
tion of the tissues of the rhizome as seen in 
longitudinal section. 

The roots. 

(a) Describe the location, form, length, diameter, 
branching, relative number, and relation to 
each other (i.e., close together or not; inter- 
woven or not) of the roots. Draw. 

The leaves. 

(a) On what surface of the rhizome are the leaves 
borne? 

(b) Note their differentiation into stem-like part, 
the petiole, and expanded portion, the blade. 

(c) What is the color of the leaf? Describe and 
suggest a probable reason for any differences in 
color. 

(d) Is the petiole glaucus (smooth, without hairs), 
or pubescent (hairy) ? 

{e) Is the blade entire, or divided into pinnae? If 
the latter, do the clefts between the pinnae ex- 



66 MORPHOLOGY AND LIFE HISTORY 

tend clear to the midrib? Compare the basal 
with the more distal clefts in this respect. 
(f) Do the pinnae appear to be all of the same age? 
If not, state reasons for considering some of 
them younger than others. Find evidence in 
your specimen of the method of formation of 
the pinnae. Are they opposite or alternate? 

(g) Describe and compare the venation of the blade, 
and of the individual pinnae. Describe any 
constant relationship between the venation and 
manner of branching of the blade. 

{h) Do the smaller veins anastomose {i.e., have their 
ends united so as to form a network), or are 
their ends free? Compare the fern leaf in this 
respect with the foliage-leaf of a seed-bearing 
plant. 

(i) Describe the appearance of very young, unex- 
panded leaves or portions of leaves. 

(k) On the ventral surface of some of the leaves find 
the brownish fruit-dots, or sori (sing, sorus). 
Describe their location. Do you find them on 
the midrib of the frond or on the individual 
pinnae? Are they between the smaller veins or 
on them? If the latter, on what part of the 
vein? Is their position constant {i.e., always 
the same) ? Are they located at the margin of 
the frond or pinna, or back from the margin? 
Describe their shape. 

(/) Do the sori occur on all the pinnae of a leaf? 
On all the leaves? Compare several specimens 
with reference to this point. 

{m) Observe, using hand lens if necessary, that the 
sorus is composed of a group of small organs 
(sporangia). What do sporangia produce? 



DIRECTIONS FOR STUDY 67 

(«) Is there a membranous expansion (indusium) 
covering the sporangia in your specimen? Ex- 
amine fronds of the other species of fern dis- 
played in the laboratory and record your obser- 
vations on this point, stating the names of the 
species observed. 

(0) Leaves bearing spores are sporophylls. Fern 
leaves that do not bear spores are vegetative 
leaves or foliage -leaves. 

(p) Do some of the sporophylls also function as 
foliage-leaves? 

(q) Examine specimens of other kinds of ferns ex- 
hibited in the laboratory and see if your answer 
to (p) is true of all ferns. Describe briefly any 
exceptions found, giving the name of the fern. 

(r) Make drawings, natural size, illustrating all 
features of the frond not clearly shown in your 
first sketch. 
D. Microscopic Characters: 
I. The rhizome. 

(a) Study prepared slides of cross-sections of the 
rhizome. (Pteris aquilina is suggested as spec- 
ially satisfactory for this study, a-g.) 

(b) With the low power survey the section and 
identify the various tissue-regions already dis- 
tinguished. 

(c) With the high power, study the epidermis, and 
describe how many cells it is in thickness, the 
variation in thickness of the cell-walls, the 
middle lamella, separating the adjacent cells, 
and the canals, or channels, extending from the 
cell-cavity outward through the cell-wall. Do 
these canals ever branch? Do they form a 



68 MORPHOLOGY AyTD LIFE HISTORY 

network? Is there any connection between 
the cell-ca\'ities of adjacent cells? 

(d) Jna. similar manner examine the cellular struc- 
ture of the h}-podermal 5clerench\'ma. 

'e ^lake drawings illustrating the features ob- 
served in (c) and (J), showing four cells of the 
epidermis,, and three or four of the underhing 
sclerench\Tna-cells. The cells should not be 
less than lo to 15 mm. in diameter. 

(/) Make similar studies and drawings of the cells 
of the parench\'ma. 

{g) Study one of the smaller fibro-vascular bundles 
and distinguish, from the circumference toward 
the center: 
(i) The out«r bundle-sheath, or endodennis. 

(2) Within the endodermis. and adjacent to it, 
a single layer of starch-bearing parenchy- 
matous cells, the phloem -sheath. 

(3) Thick- walled bast-fibers. 

(4) Larger, thin-walled cells. ha\'ing their cell- 
walls perforated, the sieve-tubes. 

(5) Associated with the cells mentioned in 
(2)— (4), parench}'ma-cells (phloem -paren- 
chyma^ containing starch. 

(6) The cells mentioned in (3)-(5) constitute 
the phloem-region, of the bundle, or 
phloem. 

(7) Within the phloem is the xylem-region, or 
xylem, composed of 

(8) Large, conspicuous tracheids, whose walls 
have ladder-like iscalariform) markings as 
seen in longitudinal section. Each tra- 
cheid is a tube, filled with air, and formed 



DIRECTIONS FOR STUDY 69 

by the fusion of several cells through the 
disappearance of their end walls. 
(9) Smaller sieve-tubes, resembling those of 
the phloem. 

(10) Thin-walled cells forming the wood-, or 
xylem-parenchyma . 

(11) Since the tissues of the fibro-vascular 
bundles are arranged circularly about a 
common center, the bundle is called a 
concentric bundle. 

(12) Compare the various bundles and see if 
they are all of similar structure. 

(13) Make a careful drawing showing the 
structure of the bundle, including all points 
mentioned under (g), (i)-(io). This draw- 
ing should be at least 75 mm. in longest 
diameter. 

The pinna. 

(a) Under the low power examine a small portion of 
one of the pinnae or pinnules not bearing a 
sorus, and note the presence or absence of 
outgrowths. 

{b) Can you observe any veins too small to be seen 
with the naked eye? If so, describe their re- 
lation to each other. 

(c) Mount a small bit of the lower epidermis, and 
describe (a) any outgrowths; (b) the stomata 
and guard-cells, stating the number, shape, 
and contents of the latter. Describe the rela- 
tive number and distribution of the stomata. 

(d) Compare the stomata of the fern with those of 
a seed-bearing plant. 

(e) Make drawings showing all features shown 
under 2, {b)-{d).' 



70 MORPHOLOGY AND LIFE HISTORY 

(/) Describe a cross-section of a pinna as shown in 
a prepared slide. Draw. Compare its struc- 
ture with that of a foHage-leaf of a higher plant. 
E. Noil-sexual Reproduction: 

1. Describe the possibilities of vegetative propagation 
of the sporophyte. 

2. With a needle remove several sporangia from a 
sorus, mount them in water and study under low 
power. 

3. Observe the differentiation of the sporangium into 
a stalk (pedicle), and a spore-case, containing 
spores. Note the walls of the spore-case, and the 
row of thickened cells, the annulus. Describe these 
cells. Note the special opening in the spore-case, 
through which the spores escape between the 
lip-cells. 

4. Make a drawing of the sporangium, about 35 mm. 
in shortest diameter, showing a portion of the 
pedicle. 

5. Study the shape and surface markings, if any, of 
a single spore. Account for the shape. Are they 
all of substantially the same size, i.e.^ is Polypodium 
a homosponis pteridophyte? 

6. Make a drawing of the spore 15 mm. in longest 
measure. 

7. Run a drop of glycerine under the cover-glass and 
carefully watch for the snapping motion of the 
sporangia by which, in nature, the spores are 
expelled. 

8. Explain the advantage to the species of ha\ang the 
spores expelled. Why would it not be as well if 
they merely dropped out of the spore-case? 
9. If suitable material is at hand, study stages in the 
germination of the spores. 



"* DIRECTIONS FOR STUDY 7 1 

10. To which of the alternating generations does the 
fern-plant belong? Why? 

11. Into what does the spore develop? 

The Prothallus 

F. Habitat: 

I. State the locations and conditions of growth of the 
prothallus (also called prothallium), (a) in artificial 
culture; (b) in nature. 

G. Naked-eye Characters: 

1. Describe the exact size (in millimeters), color, and 
shape of the prothallus. 

2. It is differentiated into a dorsal and a ventral sur- 
face? If so, how are the two surfaces distinguished? 

3. Describe the location and character of the rhizoids. 
H. Microscopic Characters: 

1. Mount a prothallus in water or clearing fluid, ven- 
tral side up, under a cover-glass. 

2. Describe the structure and contents of the cells. 

3. Describe variations in thickness. Do you find a 
thicker central portion, or cushion? 

4. Observe the growing point in the notch. 

5. Study the location and character of the rhizoids. 
Are cross- walls present? 

/. Sexual Reproduction: 

1. Among the rhizoids find small, spherical elevations, 
the antheridia. Describe their number and dis- 
tribution. 

2. Nearer the notch observe the archegonia, appearing 
to be composed of four cells, surrounding an opening 
or canal. 

3. Make a drawing, at least 5 cm. in longest diameter, 
showing all features of the prothallus thus far 



72 MORPHOLOGY AND LIFE HISTORY 

observed. By the side of this figure draw an out- 
line of the prothallus, natural size. 

4. In fresh specimens motile antherizoids or sperms 
may be found escaping from the antheridia and swim- 
ming in the water. If these are found, observe the 
body of the sperm and the cilia. How many cilia 
are there? Draw. 

5. If prepared slides are supplied, study cross-sections 
of the prothalHum passing through an antheridium 
and an archegonium. Describe accurately, noting 
the differentiation of the archegonium into a neck, 
containing a neck-canal, and a venter, containing 
an oosphere or egg* 

6. Make a diagram of the section, of the same scale 
as the drawing in 3 above, and make drawings 
showing details of structure of the antheridia and 
archegonia as seen in longitudinal section. 

7. To what class of reproductive bodies do the sperm 
and egg of the fern belong? To which of the alter- 
nating generations does the prothallus belong? 
Why? Why is it called a thallus? 

8. Is this fern monoecious or dioecious? Explain. 

9. What structure is the starting point of the sporo- 
phyte? 

10. Diagram the life history of the fern for three genera- 
tions, by continmng the following diagram; letting 
G = gametophyte; s = sperm; e = egg; S = sporo- 
phyte; sp = asexual spore: 



< 



%, 



>S-?, etc. 
s^ 

II. Make a diagram to show the Hfe cycle of the fern, 
using arrows and words, arranged in a circle. 



DIRECTIONS FOR STUDY 



73 



A'. Nutrition and Growth: 

1. Is photosynthesis carried on by both gametophyte 
and sporophyte? Transpiration? Absorption of 
water from the soil? 

2. Explain the need of stomata in the sporophyte. Are 
they present in the gametophyte? Explain. 

3. Discuss the presence or absence of a conducting 
system in the prothalhum and sporophyte. 

4. Explain how the presence of the cushion of the pro- 
thallium is related to the needs of the young sporo- 
phyte. 

5. Is the gametophyte of Poly podium ever dependent 
upon the sporophyte for its nutrition? Its exist- 
ence? 

L. Comparison of Gametophyte and Sporophyte of Poly- 
podium: 
Copy the following table into your note-book, and mark 

X after the word gametophyte or sporophyte in the 

proper column. 

Table I 















1 (U 








1 03 


I I U) 














0) 










rt c 






CO 








'2 « 


y 




"•-5 


"^ 


<u ft.2 


Generation 


a 


to 

V 

G 






09 







"(0 

2 

P. 


2 

c4 

ft 


to ^J 



1^ 


oth veg 
and re 
e funct 




u 

'0, 




4J 


<d 


s 


u 




+3 


"o 


kiX) 








<0 








.a 


2 


2*0 

CO V 


OS 


J3 


rt 


nj 




Pi 


cu 


O) 


Pi 


H 


0. 


PU 


PQ a 


m ft 


W-S-o 


Gametophyte.. 






















Sporophyte . . . 























Polytrichum conmmne (Common hair-cap moss) ^ 

A. Classification: 

Division II. Bryophyta (moss-plants). 
Class II. Musci (mosses). 
Order. Bryales. 

Family. Polytrichaceae. 
Genus. Polytrichum, 
Species, commune. 

B. Habitat: 

I. Polytrichum commune is widely distributed, growing 
in the soil in fields and woods. 

C. Naked-eye Characters: 

The Gametophyte (The ''Moss-plant") 

1. Note that there are two kinds of leafy ''moss- 
plants." The one having the cup-like tip is the 
male or antheridial plant; the other, without the 
cup-like tip, is the female, or archegonial plant. 
Compare the average height of the mature male 
and female plants. Do you find any outgrowth 
from the tip of any of the archegonial plants? 

2. Are the moss-plants differentiated into root and 
shoot? Is the shoot further differentiated? If 
so, describe. 

3. Briefly describe the extent and ramifications of the 
"root" system. Are these true roots, with root- 
hairs? 

4. Briefly describe the arrangement of the leaves on 

1 With minor modification the outline here given for the study of the 
moss will serve for species of Mnium, Funaria, or almost any other com- 
mon moss. 

74 



POLYTRICHUM COMMUNE 75 

the stem (opposite, alternate, spiral). Are the 
leaves sessile or petiolate? Simple or compound? 
Is there a midrib? Veins? Compare the dorsal 
and ventral surfaces of the leaves. Describe 
any variations in the leaves on various parts of 
the stem. Describe the margin of the leaf-blade 
(i.e., entire, notched, serrate, etc.), and the shape of 
its apex and base. 

Compare the form of the leaves in the same regions 
of the male and female plants. Note especially 
the rosette of perichaetae (modified leaves) at the 
summit of the male plant. Compare them with 
the foliage-leaves below them. 
Describe the form of the stem. Is it of uniform 
diameter? Does it branch? Compare the stems 
of the male and female plants. 
Make suitable drawings, illustrating all points 
observed under C i-6. 

The Sporophyte 

Select an archegonial plant with sporophyte (sporo- 
goniimi) attached. Distinguish the long stalk 
or seta, bearing at its summit the spore-case, or 
sporangiimi. How many millimeters long is the 
se ta ? D escribe its surface ; its diameter throughout ; 
its shape in imaginary cross-section. If it is angled, 
how many angles are there? By taking hold of 
the seta near its attachment to the gametophyte 
and carefully pulling, separate the sporogonium 
from the gametophyte. State, with full reasons, 
whether or not the tissue of the foot appears to be 
continuous with that of the gametophyte. Does 
anything like grafting of the sporophyte onto the 
gametophyte take place? 



76 MORPHOLOGY AND LIFE HISTORY 

9.. Do you find a swelling of the seta (apophysis), 
just beneath the sporangium? If so, describe and 
locate it accurately. Do its cells contain chloro- 
phyll? Of what function is, or is not, the apophysis 
therefore capable? 

10. Remove and study the cap (calyptra) that fits 
over the sporangium. Describe its shape, margin, 
character of surface, outgrowths, if any. 

11. Study the color, shape, and other features of the 
sporangium disclosed by removing the calyptra. 
Measure its length and breadth. Describe its 
attitude on the seta {i.e., erect, pendant, etc). De- 
scribe its outline in imaginary cross-section. If 
it is angled, record the number of angles. 

12. Describe the shape and surface of the hd (operculum) 
at the end of the sporangium, and just under the 
calyptra. 

13. Make a drawing, ten times natural size, showing 
the sporangium, the calyptra removed, and a por- 
tion of the seta. 

14. Carefully remove the operculum and preserve it. 
. On the margin of the sporangium, underneath the 

operculum, observe the circle of teeth-like organs 
(peristome). Record the number of teeth. Is 
this number constant? Is it always either even 
or odd? 

15. In fresh dry specimens describe the effect of the 
breath upon the position of the teeth of the peri- 
stome. 

16. Describe the membrane (epiphragm) within the 
peristome, and covering the end of the capsule. 
Is it perforated? What is its relation to the teeth 
of the peristome? 

17. Make a drawing, 30 mm. in diameter, illustrating 



^ POLYTRICHUM COMMUNE 77 

an end view of the sporangium with the operculum 
removed. Make a drawing of the operculum, 
also 30 mm. in diameter. 

18. With the razor carefully make a longitudinal section 
of the capsule, just to one side of its central axis. 
Observe the wall of the sporangium; a central 
organ (columella) ; and, between the two, a mass 
of spores. 

19. Describe the structural relation of the columella 
to the epiphragm. What, in reality, is the latter? 

20. Describe the relative number, color and attach- 
ment or non-attachment of the spores, so far as 
may be ascertained without the aid of the micro- 
scope. 

21. Make a drawing, ten times natural size, illustrating 
everything observed under 18-20. 

22. From the above observations construct a diagram of 
an imaginary cross-section of the sporangium near 
the middle. Compare the diagram with an actual 
cross-section. 

23. Carefully preserve the sporophyte in a covered 
watch-glass or other convenient moist (not wet) 
place until the next laboratory period, or proceed at 
once with the following observations (D) : 

D. Microscopic Characters: 

The Sporophyte 

1. With a sharp scalpel remove a thin piece from the 
base of the sporangium, cutting parallel to the sur- 
face, and mount it in water with the outer surface 
uppermost. 

2. Examine the mounted tissue under the low, then 
under the high power, to see if stomata are present. 
If they are, describe them and their distribution. 



78 MORPHOLOGY AND LIFE HISTORY 

Compare them with the stomata of a foliage-leaf 
of one of the higher plants, including the number, 
shape, and other characters of the guard-cells. In 
like manner compare them with the stomata of the 
fern. State, with reasons, which t}^e of stomata 
you consider the more primitive. Look for stomata 
on the surface of the apophysis. 

3. Study thin cross-sections of the sporangium (sec- 
tions of the half (C, 18) will serve). Identify the 
parts already studied, and their characters and 
relationship as seen in cross-section. Make your 
drawings at least 20 mm. in radius. 

4. Describe the shape of the spores, and their manner 
of attachment or non-attachment, as seen under 
high power. Of how many ceUs is one spore com- 
posed? Make a drawing of three spores making 
each 10 mm. in longest measure. 

5. Mount thin cross-sections of the seta, and study 
under high power. 

6. Distinguish the outer layer, epidermis. How 
many cells thick is it? Observe the central strand, 
and between this and the epidermis a thin-waUed 
tissue (parenchyma), and a layer of thicker waUed 
cells (sclerenchjmia) . State how these various 
tissues may be distinguished from each other. Of 
what value is the sclerenchyma? The central 
strand is comparable with the fibro-vascular bundle 
of the seed-bearing plants. Draw. 

The Gametophyte 
The Leaf. 

7. Remove an entire leaf and mount it in water. Ob- 
serve under low, then under high power. 

8. How many cells thick is it. Is it of uniform thick- 



% POLYTRICHUM COMMUNE 79 

ness? Describe. Are stomata present? Why? 
How is the midrib distinguished? Describe the 
leaf-margin and apex. Describe any differences 
in the two sides of the leaf. 
9. Describe fully the contents of a single cell, as 
observed under high power. 

10. Illustrate by suitable drawings all features observed 
under D, 7-9. 

The Stem. 

11. Study, under the low power, cross-sections of the 
stem mounted in clearing fluid (or use prepared 
slides) . 

12. Describe the tissues observed, and their relation to 
each other. Compare the structure of the game- 
tophyte-stem, as seen in cross-section, with that of 
the sporophyte-stem, and name the tissues of the 
former, using the terms given above {D, 6). 

13. Illustrate by a drawing, at least 50 mm. in diameter, 
the structure of the stem as seen in cross-section. 

E, Non-sexual Reproduction: 

1. In some mosses a second gametophyte often devel- 
ops from the tip of an older plant. This is called 
proliferation. Frequently this may be repeated a 
number of times, forming a chain of plants, each 
younger one growing out of the apex of the next 
older one. Examine the material at hand, and, if 
such a condition is found, describe it, with drawing. 
What kind of reproduction is this? 

2. Explain the advantage to the species of the elon- 
gation of the seta. 

3. If stages in the germination of the spores are avail- 
able, study this process. The structure imme- 
diately developed from the spore is the protonema. 



8o "^MORPHOLOGY AND LIFE HISTORY 

Describe its color. Is it simple or branched? Are 
cross-walls present? 

4. At certain points on the protonema observe buds. 
These buds develop into either male or female game- 
tophytes (gametophores). 

5. Which generation of the moss-plant always devel- 
ops from the spore? Compare this with the case in 
the fern. 

F. Sexual Reproduction: 

The antheridia 

1. Take a male gametophyte and, with a dissecting 
needle, carefully remove some of the antheridia, 
borne in the rosette at the summit of the plant. 
Mount them in water, and study them under the 
microscope. 

2. Describe the shape and other structural features 
of the antheridia. What is their color? Compare 
them with the antheridia of the fern. 

Do you find paraphyses associated with the anther- 
idia? If so, describe them, and state how they 
may be distinguished from the antheridia. 

4. If prepared slides are available, study longitudinal 
sections through the tip of the male gametophyte, 
observing the mode of attachment of the antheridia. 

5. With high power study the sperms (spermatozoids) 
within the antheridia. 

6. In fresh specimens the sperms may be seen swim- 
ming about in the water. If motile sperms are 
present, endeavor to make out the number and 
character of their organs of locomotion (cilia). Do 
the cilia precede or follow as the sperm moves for- 
ward? Do the motions of the sperm appear to be 
purposeful or not? Give reasons for your answer. 



* POLYTRICHUM COMMUNE 8l 

7. Make drawings showing all features observed under 
F, 1-6. The antheridia should be at least 25 mm. 
long; the body of the sperms 10 mm. long. 

The archegonia 

8. With the female gametophyte make studies as 
directed above (F, 1-4). 

9. In the archegonium distinguish the venter, neck, 
and lid-cells. Is the archegonium sessile or stalked? 

10. If prepared slides are available, identify the 
oosphere, or egg, and the neck-canal. How many 
cells thick is the wall of the archegonium? Is this 
uniform? 

11. Make a drawing, at least 35 mm. long, showing all 
features observed under F, 8-10. 

12. Describe the conditions, processes, and organs in- 
volved in sexual reproduction in the moss. Explain 
whether or not it is of advantage to the moss-plants 
that they grow so close together. 

13. Into what does the fertilized egg develop? Where 
does it develop? 

G. Nutrition and Growth:"^ 

The gametophyte 

1. Is the gametophyte of the moss capable of elabor- 
ating its own carbohydrate food? Explain. Is it 
dependent upon the sporophyte at any period of its 
existence? Explain. 

2. How does the possession of leaves affect the surface- 
area of the chlorophyll-bearing tissues? Explain 
how this affects the process of photosynthesis. 

^ This may be assigned for home work and serve as the basis of class 
discussion, or of written work to be handed in. 
6 



82 MORPHOLOGY AND LIFE HISTORY 

3. State the organs and processes by which water and 
inorganic salts are taken in by the gametophyte. 

4. Explain the presence or absence of stomata in this 
plant. 

5. By what organs is the respiration of the gameto- 
phyte carried on? 

6. Does the gametophyte have to elaborate food in ex- 
cess of its own needs? Explain. Explain the need 
or lack of need of conducting tissues in the gameto- 
phyte. 

7. Name two ways in which the gametophyte is kept 
rigid and erect. 

The sporophyte 

8. Can the sporophyte lead an independent existence 
at any time in its history? Explain. 

9. By what organ or organs, by what process, and from 
what source are water and dissolved food substances 
taken into the sporophyte? 

10. Is photosynthesis possible in the sporophyte at any 
period of its existence? What is the source of its 
carbohydrate food? 

11. Explain the need or lack of need of conducting tis- 
sues in the sporophyte. Compare the degree of 
development of these tissues in the sporophyte and 
gametophyte of the moss. 

12. Explain the significance of the presence or absence 
of stomata in the sporophyte. 

13. Refer to the question inF, 13, and explain the origin 
of the calyptra. To which generation does it be- 
long? Explain. 

14. Explain the advantage of sclerenchymatous tissue 
in the sporophyte. Describe the distribution of 



POLYTRICHUM COMMUNE 83 

this tissue in the seta, and explain whether or not 
this is an added advantage. 

15. After the sporophyte of Polytrichum begins to de- 
velop, does it grow continuously until maturity, or 
does a period of prolonged rest intervene? Is the 
same true with the sporophyte of the fern? 

16. As directed in 7, lo, p. 72, diagram the life history 
of the moss. 

17. Outline the life history of the moss, as described in 
/, II, p. 72. . 

H. Comparisons: 

1. Write the following names of organs of the gameto- 
phyte of the moss in a column, and opposite them, 
in another column, the names of the corresponding 
organs of the fern; thallus, rhizoid, antheridiophore, 
archegoniophore, antheridia, sperm, archegonium, 
egg, paraphyses. 

2. In a similar manner compare the organs of the sporo- 
phytes of the two plants, adding the names; sto- 
mata, foot, calyptra, columella, apophysis, sporan- 
gium. 

3. In a third column make a list of organs of the moss 
not found in the fern; in a fourth column, the organs 
of a fern not found in the moss. 

4. Compare the degree of organization of the gameto- 
phytes of the fern and the moss, as illustrated by 
Polypodium and Polytrichum. 

5. In like manner compare the sporophytes of the two 
classes of plants. 

6. State several reasons for regarding Polytrichum as 
either more or less highly organized than Poly- 
podium. 



Marchantia polymorpha (A Liverwort) 

A. Classification: 

Division II. Bryophyta (moss-plants). 
Class I. Hepaticae (liverworts). 

Order. Marchantiales (marchantia-f orms) . 
Family. Marchantiaceae. 
Genus. Marchantia. 
Species, polymorpha. 

The Gametophyte 

B. Habitat: 

I. This plant grows very abundantly on the soil of 
flower pots and benches in nearly all greenhouses. 
In places it becomes a great annoyance to gardeners, 
and is very difficult to get rid of. Out of doors it 
grows in moist, shady places, frequently on rocky 
ledges by streams. 

C. Naked-eye Characters: 

1. Examine first a non-" fruiting " specimen. 

2. Is the plant-body a thallus? Describe its color, 
outline, and manner of branching. What term is 
appHed to this manner of branching? Does the 
plant possess dorso-vertral differentiation? If so, 
how are the dorsal and ventral surfaces distin- 
guished? 

3. Note the texture of the plant, to be ascertained by 
carefully breaking off a piece of fresh thallus. 

4. Describe the appearance of the dorsal surface. The 

84 



MARCHANTIA POLYMORPHA 85 

small areas into which it is marked off are areolae. 
In the center of each areola find evidence of a 
stoma. Is there a midrib? 

5. The cup-shaped structures on the dorsal surface 
are called cupules. Do they occur on definite 
portions of the thallus {i.e., margin, midrib, etc.), 
or irregularly? Describe their color, shape, height, 
diameter, margin. Are they sessile or stalked? 

6. The non-sexual (vegetative) reproductive bodies 
within the cupules are brood-buds, or gemmae 
(sing., gemma). Describe the color, shape and 
size of one (use hand lens) . How are they attached 
to the plant? Do all the cupules contain them? 
Explain your observation on this point. 

7. Examine the ventral surface of the plant. De- 
scribe its color and surface markings, and compare in 
these respects with the dorsal surface. 

8. Note the root-like filaments or rhizoids. Describe 
their shape, color, dimensions, and distribution 
over the ventral surface. 

9. Find purple, leaf-like structures (scales) among the 
rhizoids, and describe their form, position, and 
distribution. 

10. Make careful drawings, showing: 

(a) The plant-body, natural size. 

(b) The surface markings of the dorsal surface, 
enlarged ten times. 

(c) A cupule, side view in perspective, enlarged 
ten times. . - 

(d) An outline of a gemma enlarged ten times. 

11. Make a diagram of an imaginary cross-section of 
the plant-body, passing through one or more cupules 
(ten times natural size) . Label all parts of the 
drawings. 



86 . MORPHOLOGY AND LIFE HISTORY 

D, Microscopic Characters: 

1. The rhizoids. 

(a) With the forceps carefully remove a few of the 
rhizoids and mount them in clearing fluid. 
Examine them first under low, then under high 
power. 

(h) Do you find different kinds of rhizoids? If so, 
how are they distinguished? Are there cross- 
walls? Describe the contents of the rhizoidis 
Do they branch? Explain the shape of their 
tips, and the thickness of their cell-walls. 

2. The gemmae. 

(a) Remove several gemmae with a scalpel, being 
careful not to cut or otherwise injure them, 
and moimt them in a drop of water. Examine 
with low power. 

(6) Are the gemmae more than one cell thick? Is 
their thickness uniform? Describe. 

(c) Find on the margin the scar, where the gemma 
was attached to its pedicle, or stalk. 

{d) Find two vegetative notches, i8o° apart. How 
do they differ from the scar? Find papilla-like 
cells in these notches. Do they contain chloro- 
phyll? Do they secrete mucilage? In the 
apex of each of these notches is a vegetative 
point from which a new thallus will develop. 
Mucilage protects it. 

ie) Are there any surface outgrowths? Is there 
dorso-ventral differentiation? Compare them 
in this respect with the thallus to which they 
give rise. So far as you can detect, would it 
make any difference which side up the gemma 
lay when it was sown? 



MARCH ANTIA POLYMORPH A 87 

(/) In the cells of a gemma do you find chloroplasts? 
Nucleus? Oil drops? 

(g) Note the larger cells with clear contents from 
which the rhizoids will develop. Do they con- 
tain chlorophyll? 

(h) Make a drawing 50 mm. in diameter, showing 
all the features observed under D, 2. 

(f) Draw the outline of an imaginary cross-section 
passing through the center of a gemma. 

The thallus. 

(a) Under high power study the surface cells and 
stomata. How many guard-cells are there? 
Compare the stomata of Marchantia with those 
of a foliage-leaf of a higher plant, and of the 
moss and fern. 

{h) Study cross-sections of the plant mounted in 
clearing fluid. 

ic) The careful study of the structure of the foliage- 
leaf, already made, makes it unnecessary 
to give detailed directions for these observa- 
tions. Frame your own questions, to be 
answered by observing the mounted section. 
Note especially whether the tissues are differ- 
entiated, and, if so, compare with a foliage-leaf 
in this respect. 

{d) Look for sections passing through stomata, 
and compare their structure with that of the 
stomata of the leaf. What causes the surface 
appearance of the margins that delimit the 
areolae? 

{e) Describe the place and mode of origin of the 
rhizoids; of the cupules. 

(/) Is the thallus of the same thickness throughout? 

{g) Describe the chloroplasts. In some of the 



88 MOKPHOirTY -.>r: iirz zisir-v 

cdls bic-^v:: oil globules nay :e :: serve i. 
If these are found, ce5:::':e :"::eir .ccadoz. 
and rdathre dze. Do the :e^ e that contain 
oil ^ob^ules also contain p::::p-3.sz:' I:i:er 
the source of the cSL 
(A) Make drawings to iUnstiateallfeatiiies observed 
under D. 3. 
E. VegdaUvePr r:: :?^: 

1. There are :~: Trays in which Marchanda can 
propaga t e i : 5 e Lf without the int^vention of gametes. 
In the frs: race, a portion of the thallus brokoi 
<^iscap? .e :: leveloping into a mature individuaL 
S : =1 e ~\i a 1 : ugh not sharply, distinguished from 
:h:5 method is reproduction by niea:i5 :: tbe 
gezins. State two differences be :~eer. a zezizia 
and a fern or moss ^x>re. 

2, Inrorprrate the above fart? 'r/. : v:ur nrtes at this 
pi": using your own la- r.: a re 3.11 s::.:e :: ~ha: 
^ri :: reproduction each ;; rJie ab; e zie:Ji;is 

I. Srui; par .5 jia\-iiig the upii^t stalks which bear 
the seruai :ei:: luctive organs. 

The aniheridial branch 

Naheirtye Ckaraders: 

(a) The stalks having the mushroom-shaped tops 
bear the antheridia, and are hence called the 

a-:herM:a". ::ar-:be5 :: antheridiophores. The 



C .:■- - ;i - 



stalk, is :iie antheridial receptacle. 
(6)- -Study az i ies:ri:e :'ae s.al^s :f the antheridio- 
rhores. Oz ~ -a: :eri : n of the thallus are these 



MARCHANTIA POLYMORPHA 89 

structures borne? On which surface do they 
originate? State their average height in miUi- 
meters. Describe the grooves on the surface. 
How many are there? 

(c) Describe the color of the stalk. Are stomata 
present? Epidermal hairs or other outgrowths? 
If so, describe. 

(d) Do you find any antheridiophores that branch? 

(e) Describe carefully the appearance of the upper 
surface of the antheridial receptacle, noting 
the occurrence and distribution of any struc- 
tures or surface marks. 

(J) Is this surface perfectly plane? If not, describe. 

(g) Make drawings, twice natural size, showing 
all points observed under F, i, (a)-(/), including 
a cross-sectional view of the stalk. 
Microscopic Characters: 

(h) Study and describe with drawings (5 cm. 
in diameter), the structure of the stalk of 
an antheridiophore as seen in cross-section. 

(i) Using prepared slides, study thin longitudinal 
sections passing through a receptacle and 
portion of the stalk. Is there a differentiation 
into epidermis and other tissues? Describe 
in detail. Note the intercellular air-spaces. 
In what part of the structure do they occur? 
Suggest any advantage these air-spaces may be 
to the plant. 

(k) Observe the chambers opening at the surface 
through necks, and containing the antheridia. 
How many antheridia in each chamber? De- 
scribe their shape, and mode of attachment. 
How many cells thick is the wall of the anther- 
idium? Do the wall-cells contain chlorophyll? 



90 MORPHOLOGY AND LIFE HISTORY 

(/) Describe variations in the size of the antheridia, 
and explain. Locate them according to size. 

(;;0 Do you find papillae (paraphyses) at the base 
of the antheridia? If so, of how many cells are 
they composed? Describe their shape and 
appearance. 

(n) Describe the appearance of the contents of an 
antheridium. In the mature antheridium the 
contents are mature antherozoids or sperms. 
Younger antheridia contain sperm-mother- 
cells. Describe their appearance accurately. 

(o) Illustrate by suitable drawings all the features 
observ^ed under i^, i, (i)-{n). 

The archegonial hrayvch 

Naked-eye Characters: 

(j>) The stalks ha\'ing the umbrella-shaped tops 
bear the female reproductive organs or arche- 
gonia, and are called archegoniophores. The 
expanded portion at the top of the stalk is the 
archegonial receptacle. 

(g) Do the archegonial and antheridial branches 
occur on the same plants? Measure the height 
of the stalks of several mature archegoniophores, 
and compare their average height vv^ith the aver- 
age height of the stalk of the mature antheridio- 
phore. Is the stalk of the archegoniophore 
grooved? 

(r) Describe the markings of the upper surface of 
the receptacle, and compare it with the dorsal 
surface of the thallus. Are stomata present? 
Record the number of rays on your specimen. 
Compare several specimens on this point. 



"^ MARCHANTIA POLYMORPHA 9 1 

(5) Describe the under surface. Note the fringed 
membranes, (perichsetiimi). 
Microscopic Characters: 

(/) Study and describe, with drawings (5 cm. in 
diameter), the structure of the stalk of an 
archegoniophore as seen in cross-section. Com- 
pare this with the antheridiophore (F, {h), p. 

89). 

(w) Using prepared slides, study longitudinal sec- 
tions of the receptacle passing through one of 
its arms. If fresh or preserved material is at 
hand in sufficient quantity, the study may be 
made from material "teased out" on the 
slide. 

{v) Study the tissues of the receptacle. Is there an 
epidermis? Stomata? Describe (a) the tis- 
sues just beneath the surface layer of cells; 
{h) those more deeply seated. 

{w) Observe the flask-shaped archegonia hang- 
ing from the lower surface of the receptacle. 
Can you distinguish two regions — ^venter and 
neck. Note the passage, or neck-canal, leading 
from the venter through the neck, and opening 
at the summit. How many cells thick is the 
wall of the archegonium? Compare with the 
archegonia of mosses and ferns. 

{oc) Surrounding a mature archegonium observe the 
section of a cup-like structure, the perigynium. 

(y) Within the venter of an archegonium just 
matured observe a single-celled ovum, or egg. 

(2) Make drawings illustrating all features shown 
under (w) — (y), and preserve the mounted 
section for subsequent study. 



92 MORPHOLOGY AND LIFE HISTORY 

G. Physiology: 

1. Is photosynthesis possible with the thallus? The 
antheridiophore? The archegoniophore? What 
correlation do you find between structure and 
function in this respect in the archegoniophore? 

2. Explain the nutrition of the non- chlorophyll-bear- 
ing cells of the gemmae. What is their nutritive 
relation to the gemma as a whole? 

3. Is the gametophyte capable of an independent ex- 
istence? Thoughtfully consider and then describe 
the correlation between structure and function in 
this respect. 

4. In mature specimens grayish drops of liquid may 
often be found exuding on the dorsal surface of the 
antheridiophores. This liquid contains active an- 
therizoids, or sperms. Mount some of it in water, 
and, under high power, observe the motion, organs of 
motion, and other structural features of these sperms. 

5. When longitudinal sections of mature archegonia 
are mounted in water containing active sperms the 
behavior of the latter toward the former may be 
readily observed. If your material is suitable, 
make these studies. 

6. How only can the sperms reach the egg? What 
external conditions would be favorable for this? 

7. Of what advantage is it to the sporophyte to have 
the egg retained in the venter of the archegonium? 
Would this be of as great advantage in any aquatic 
plant, as in a land plant? Why? 

8. Is the small size of the sperms of any special advan- 
: ^tage to the plant? Explain. 

]: 9. Explain any advantage in the greater height of the 
mature archegoniophore over that of the antheridio- 
phore. 



> MARCHANTIA POLYMORPHA 93 

lo. Enumerate several facts that insure a wide distribu- 
tion of Marchantia. 

The Sporophyte 

A . Origin of the Sporophyte: 

I. What is the process of the fusion of the egg and 
sperm called? What is the body that results 
from this fusion called? This body, by successive 
cell-division, develops into the sporogonium or 
sporophyte. 

B. Naked-eye Characters: 

1. In a mature specimen observe the small bell- 
shaped organs (sporangia) pendant on a stalk 
between the perichaetia. The sporangia and stalk 
together form the sporogonium, or sporophyte stage 
of Marchantia. In fresh mature specimens an 
orange-colored mass containing spores is easily seen 
at the end of the sporophyte. Are the sporogonia 
borne on a line with the rays or between the rays? 

2. Make drawings, four times natural size, showing the 
archegoniophore as seen from (a) the top; (b) the 
side; (c) the underside. 

3. After making the drawings, as directed in B, 2, 
carefully dissect out one mature sporogonium and 
place it in a watch-glass to examine. Mak^ a 
drawing 50 mm. long, showing all features observed, 
labeHng the foot, stalk, and sporangium. Write a 
brief but clear description of the sporogonium. 

C. Microscopic Characters: 

I. If prepared slides are available of sections passing 
through the archegonia (F (w) above), find various 
stages in the development of the sporophyte within 
the archegonium. In nearly mature specimens 



94 MORPHOLOGY AND LIFE HISTORY 

observe the attachment of the sporophyte to the 
receptacle by means of the foot. This study may be 
made to advantage with fresh or preserved material 
teased out on the sUde. In such preparations there 
will be observed, surrounding the sporogonium, the 
membrane formed by the growth of the perigynium. 
2. In the mount already made (or in a fresh mount of 
the orange-colored mass referred to in (5, i, ^. 93), 
observe the spore-mother-cells (sporocytes) or, in 
older specimens, the spores (in strands or separate, 
depending on the stage of development), and the 
elongate elaters. What is the size of the spores, and 
the number of cells of which they are composed? 
Describe their shape, and any surface marks ob- 
served. Describe any marks on the elaters. Of 
how many cells is an elater composed? Mount, dry^ 
some of the mass that contains elaters, and observe, 
under the low power, their behavior as water is 
added. 

3. Are the antheridiophores and archegoniophores 
sexual organs? Why? What are the sexual organs 
of Marchantia? 

4. Name and classify (sexual or asexual) four different 
kinds of reproductive bodies produced by this plant. 
Consider carefully whether the spores, produced 
by the sporophyte, are sexual or asexual reproduc- 
tive bodies. 

D. Physiology: 

1. Can photosynthesis take place in the sporophyte? 
Explain your answer. 

2. From what source, by what organ or organs, and 
by what physical process does the sporophyte ob- 
tain its water and dissolved food? Compare it 
with the gametophyte in this respect. 



MARCHANTIA POLYMORPHA 



95 



E. Comparison of Gametophyte and Sporophyte: 

1. Compare the degree of development or organiza- 
tion of sporophyte and gametophyte. 

2. Copy the following table into your laboratory note- 
book and mark x after the word gametophyte or 
sporophyte in the proper column. 







Table II 




















1 ?J 


0) 


en 


1 


•o 


t>. 








G 

BJ 

bO 
u 
O 

<u 


G -M 
O 0) 


_-+J 


<u 


ct] 




CO 


Generation 


,o 






a 

bo 
to 


o 


ns, bo 

;ive 

active 


si 




is 


0. 


^ G 


M 




A 


Q rt-O 


Ot:} 




u 

'E 

(U 
Pi 


o 
u 
o 

o 


o 
o 

Pi 


BJ'S 


> 

-.3 


o 

CM 


V 


Functi 
veget 
repro 


'■5 2 


Gametophyte 




















Sporophyte 

























3. State reasons why you consider Marchantia higher 
or lower than (a) the moss; (b) the fern. 

4. Diagram the Hfe cycle of Marchantia, as directed 
for the fern (/, 11, p. 72). 

5. Indicate the life history of Marchantia for three gen- 
erations, as directed in /, 10, p. 72. 

6. Does the gametophyte ever produce another game- 
tophyte directly? Does the sporophyte ever pro- 
duce another sporophyte directly? If so, explain 
how. What phase intervenes between two gameto- 
phytes in the alternation of generations? Between 
two sporophytes? Is this always the case so far 
as your own studies show? Explain what is meant 
by the expression, *' alternation of generations." 



Fucus vesiculosus (Bladder wrack) 

A. Classification: 
Division I. Thallophyta. 

Subdivision I. Algae. 

Class III. Phaeophyceae (brown algae). 
Order. Fucales. 
Family. Fucaceae. 
Genus. Fucus. 
Species, vesiculosus. 

B. Habitat: 

I. Ascertain the habitat of this plant from your read- 
ing and class discussions, and record it in your 
laboratory notes at this place. 

C. Naked-eye Characters: 

1. These characters may be best studied by floating a 
fresh specimen in a dish of sea-water. Material 
preserved in formalin should be rinsed under the 
tap, and then floated in fresh water. 

2. Describe the color, shape, and size of the thallus. 
Does it form lateral branches or approximately 
equal terminal branches (dichotomy, forking). 

3. Do you find any holdfasts, or organs of fixation? 
If so, describe them. State reasons why you think 
they are true roots or not. 

4. Is there a midrib? A stalk, or stipe? Do you 
consider that the plant is differentiated into root, 
stem, and leaf? Give reasons. 

5. Describe the distribution of bladders. Why is this 
species called ^'vesiculosus^'? 

96 



FUCUS VESICULOSUS 97 

6. Observe the swollen tips, receptacles. Do the tips 
of all the branches bear receptacles? How may 
they be distinguished from the bladders? 

7. Carefully note the dot-Kke projections on the re- 
ceptacles. Find the circular openings in these pro- 
jections, the ostioles. 

8. Do you find ostioles elsewhere than on the recep- 
tacles? If so, describe their distribution over the 
surface of the thallus. Where are they not found? 

9. Observe carefully the emarginate tips of the 
branches that do not bear receptacles. Do you 
find a groove in these tips ? If so, is it in the plane 
of the thallus, or not? 

10. Make careful drawings, natural size, showing all 
points noted under C. 
D. Microscopic Characters: 

I. Mount in water thin cross-sections taken through 
the thin expanded portion of the thallus, and study 
under the low power. 

Note the differentiation of the tissue into central 
tissue or medulla, and a cortical tissue. How are 
the two distinguished? 

3. Observe that the outer layer of cells of the cortical 
tissue is further differentiated into an epidermoidal 
tissue. Describe it. This outer layer is not a true 
epidermis, like the outer layer of cells of the leaf. 
In the younger portions of the thallus its cells, by 
division, give rise to the cells which form the under- 
lying tissues. None of the algce possess a true 
epidermis. , 

4. Is starch present in the cortical tissue? Chlo- 
rophyll? Note the layer of cuticle on the outer 
cell-walls of the epidermoidal layer. 

<. Note that the cells in the medulla tend to form a 



98 MORPHOLOGY AND LIFE HISTORY 

thread-like network. Does starch occur in this 
tissue? Some of the cells unite, end to end, form- 
ing tubes to conduct liquids. 

6. Between the cells of both cortex and medulla is a 
mucilaginous layer, formed by the swelling and 
chemical transformation of the middle lamella, 
or layer that separates adjacent cell-walls. 

7. Make a drawing showing the differentiation of 
tissues from the surface to the center of the thallus. 

8. Sterile Conceptacles: Secure sections passing through 
one or more of the ostioles that do not occur on the 
receptacles. These ostioles will be found to open 
into spherical or pear-shaped cavities (conceptacles) 
imbedded in the cortical tissue. In viewing a cut 
end of the thallus with the naked eye, these cavities 
appear as minute dots underneath the epidermoidal 
layer. 

9. Observe in these conceptacles, under the low power, 
numerous long hairs (paraphyses). Of how many 
cells is each composed? Do they extend through 
the ostioles to the surface? With what are they 
connected? 

E, Physiology: 

1. Of what advantage to an aquatic plant may the 
air-containing bladders be? 

2. Does the plant grow attached to a substratum? 
If so, how? 

3. How do you think the plant takes in its food ele- 
ments? 

4. Ascertain if the plant has chloiophyll. Is photo- 
synthesis possible? 

5. Would it be an advantage to this plant to have a 
system for conducting liquid nutrients from one 
place to another? Is such a system present? 



> FUCUS VESICULOSUS 99 

In attempting to answer this last question recall 
the habitat of Fucus. 

F. Vegetative Propagation: 

1. Vegetative propagation is accomplished by the 
breaking off of branches which may float away 
and become established as new individuals. 

2. Frequently, by a process of regeneration, dwarf 
branches are formed where portions of the thallus 
have been torn away. Do you find instances of 
this in the material at hand? 

G. Sexual Reproduction: 

1. The sexual reproductive organs of Fucus are borne 
in fertile conceptacles, imbedded in the cortical 
tissue of the receptacles. In Fucus vesiculosus the 
conceptacles containing the female organs are on 
different plants, i.e,, the plants are dioecious. In 
other species they are both on the same plant, while 
in still other species {e.g., F. edentatus) both kinds 
of organs are in the same conceptacle. In the two 
latter cases the plants are monoecious. 

2. The Male Conceptacles: 

{a) Examine a longitudinal section of a male 
conceptacle, passing through the ostiole. Note 
the outline of the cavity. Describe its wall. 

(b) Observe the filaments (paraphyses) within the 
cavity, and describe the length, diameter, 
shape, and structure of one of them. Do any 
of these filaments project through the ostiole? 
Explain the feeling as a receptacle is taken be- 
tween the thumb and fingers. 

(c) Are the filaments that pass through the ostiole 
similar to those that do not? On the latter 
observe the small ellipsoidal organs antheridia. 
Where and how are they attached? How 



lOO MORPHOLOGY AND LIFE HISTORY 

many on each hair? Observe their contents, 
the sperms (antherozoids, spermatozoids) . 
(d) Make a drawing at least 50 mm. in longest 
diameter, illustrating all the above structures. 

3. The Female Conceptacles: 

{a) Study a longitudinal section passing through 
a female conceptacle, as directed above 
(G, 2). Compare them in all points with 
the male conceptacles. 

{b) Observe the egg-bearing organs, oogonia. 
Describe their shape, size, color, place and 
mode of attachment, and number, and 
compare them in these respects with the 
antheridia. 

{c) Describe the structure of the wall of the 
oogonium, noting especially whether it is 
composed of cells. 

{d) Study the contents (oospheres, or eggs) of 
the oogonium. How many are there? 

{e) Make drawings showing all these points, 
as directed in G, 2 {d) . 

4. The Fertilization of the Egg: 

(a) Observe fresh plants that have been hang- 
ing in the air for about six hours, and see 
if you can observe an orange-colored fluid 
exuding from the ostioles of the male con- 
ceptacles. If so, mount some of this fluid 
in sea-water and examine it under the high 
power. 

(b) Note the antheridia floating about, and the 
escaped sperms. Do the latter possess the 
power of locomotion? If so, how do they 
move? Describe their shape, relative size, 
and color. 



FUCUS VESICULOSUS lOI 

(c) Make a drawing of three or four sperms, 
with the body about lo mm. long. 

(d) In a similar way, find the fluid exuding 
from the female conceptacles. What is its 
color? Mount a drop of it in sea-water 
and examine with the high power. 

(e) Do you find any oogonia? Any free eggs? 
If so, how are the latter freed from the 
oogonia? Do they possess the power of 
locomotion? Compare their size with that 
of a sperm. 

(f) Make a drawing (50 mm. in diameter) of 
an egg. By the side of the egg; draw three 
sperms to the same scale, showing the 
relative size of egg and sperm. 

(g) Prepare a mount containing both eggs and 
sperms, and endeavor, if possible, to fol- 
low the action of the sperms toward the 
egg, and the fusion of the two cells. With 
what act is fertilization completed? 

(h) Do you consider Fucus a more highly or a 
more lowly organized plant than Mar- 
chanfia? Give reasons for your answer. 



Vaucheria sessilis (Green felt) 

A. Classification: 
Division I. Thallophyta. 

Subdivision I. Algae. 
Class II. Chlorophyceae. 

Order. Siphonales (Siphon-algae). 
Family. Vaucheriaceae. 

Genus. Vaucheria. (The only genus in 

the family.) 
Species, sessilis. 

B. Habitat: 

From your reading, class work, and material at hand, 
ascertain and record at this point in your notes the 
kind of localities where this plant occurs. 

C. Naked-eye Characters: 

Describe the color and "feel" of this plant, and the 
general form of the plant-body. What is the signifi- 
cance of the common name ''green felt"? 

D. Microscopic Characters: 

1. Mount a portion of the material in water. 

2 . Is the plant branched ? If so , is the branchin g lateral 
or dichotomous (i.e., forked)? 

3. Do you find cross- walls? Does the plant seem to 
be composed of cells? What is the outline of its 
cross-section? 

4. Can you detect any signs of division into root and 
shoot? Do all portions of the filaments appear 
equally fresh and vigorous? Describe. 

5. Do you find, on the end of any of the filaments, 

102 



^. VAUCHERIA SESSILIS IO3 

holdfasts? If so, describe them, and state their 
use to the plant. 

6. Can you detect one or more nuclei? Any vacuole 
or vacuoles? Any individual chromatophores or 
chloroplasts ? If so, what is their position and 
shape? 

7. Describe the arrangement of the protoplasm within 
the filament. 

E. Physiology: 

1. Explain whether, or not, photosynthesis and respira- 
tion are possible with this plant. 

2. Do you find any chromatophores dividing? 

3. Do you find oil globules within the plant? Test 
dechlorophyllized plants with iodine for starch. 

4. How are mineral matter and carbon taken into this 
plant? Explain the need or lack of need of special 
structures for conducting food and food elements 
from one part of the plant to another. Are such 
structures present? 

5. Why is the plant not crushed by the weight of the 
water (when it grows in water), or by the cover- 
glass? 

6. Can you detect any movement of the protoplasm? 
Observe carefully on this point. 

7. Make careful drawings showing all features to which 
attention has been directed under D, and E, 2. 

F. Asexual Reproduction: 

1. Carefully examine the tips of numerous filaments 
and see if you find any of them slightly enlarged, 
and cut off from the rest of the filament by a cross- 
wall. Such a differentiated portion of the thallus 
of Vaucheria is a sporangium ; its contents a spore. 

2. If you are fortunate enough to have material at a 
suitable stage of development, you may, by care- 



I04 MORPHOLOGY AND LIFE HISTORY 

ful observation, observe a spore escaping from the 
opening in the tip of the sporangium. If so, give 
careful attention to the mode of locomotion of the 
spore, and describe how its locomotion is accom- 
plished. Since it has motion (as animals do) it is 
called a zoospore. The zoospore soon comes to 
rest. 

3. If the material contains germinating zoospores, 
carefully describe them. 

4. Make drawings illustrating all you have observed 
under F. 

G. Sexual Reproduction: 

I. In "fruiting" material, observe the lateral organs 
that bear the gametes. These are the reproductive 
organs. As is seen, they are of two kinds. 
2. The larger, oval-shaped organ is called the oogonium. 
Is the oogonium cut off from the parent filament 
by a wall? On one side observe the rostnun, or 
beak, through which is an opening or pore. In 
material at a suitable stage may be observed a 
portion of the contents of the oogonium being 
voided or discarded. The protoplasm that re- 
mains in the oogonium now becomes organized into 
the larger gamete or egg (oosphere). Is its wall 
composed of cells, or is it a unicellular organ? 
3. By the side of the oogonium^ find a slender branch, 
usually recurved at the end. Is this branch cut off 
from the parent filament by a wall? Is the tip 
cut off from the rest of the branch? This tip bears 
small gametes, that swim about by means of two lash- 
like cilia. They are the spermatozoids or sperms. 

^ If the species is V. geminata, instead of V. sessilis, the reproductive 
organs will be found on the same lateral branch. The above directions 
will not apply in detail to any species except V. sessilis. 



VAUCHERIA SESSILIS 105 

What is the organ that bears the sperms called? 
The base of the antheridial branch is the pedicel, 
or stalk. 

4. Can you detect any sperms escaping? I( so, 
observe and describe them carefully. See if you 
can find any empty antheridia. 

5. Make careful drawings showing all points observed 
under G. 

6. Is there a division of physiological labor in Vauch- 
eria? Explain in detail. 

7. Show, by a diagram, the life cycle of Vaucheria. 

8. State the difference between conjugation and 
fertilization. 

9. Draw an ideal diagram of a complete plant, showing 
all structures, and stages of their development. 



Spirogyra sp. (Pond scum, Gkeen silk)^ 

A. Classification: 
Division I. Thallophyta. 

Subdivision I. Algae. 
Class II. Chlorophyceae. 
Order. Conjugales. 
Family. Zygnemaceae. 
Genus. Spirogyra. 
Species, sp. {i.e., not determined). 

B. Habitat: 

Ascertain from your own observations and from the 
text, and record at this point in your notes, the habitat 
of Spirogyra. 

C. Physiology: 

1. Explain, clearly but concisely, how the bodily form 
of this plant is maintained. Account for any 
variations in the shape of the cells. 

2. Do you find any roots or other organs for anchoring 
the plant to the substratum? Do you think the 
plant is suitably organized for growing in running 
water? Explain. State a reason why roots are 
not necessary for this plant. 

3. Explain the presence or absence of stoma ta. Do 
you find a cuticle? Is photosynthesis possible with 
Spirogyra? Respiration? Explain. 

1 The morphological characters of this plant have already been studied 
(pp. 1 1- 1 5). They should now be carefully reviewed, preparatory to the 
consideration of the physiology and reproduction of the plant. 

2 True cuticle does not occur, but a modification of the outer portion 
of the cell-wall, called the sheath, and which gives the plant its slippery 
*'feel," is similar to cuticle, though not identical with it. This sheath 
is difficult to observe directly, though it may sometimes be identified on 
the outside of the filament at the places where the cross-walls occur. 

106 



SPIROGYRA SP. 107 

> ■ 

4. Can you detect any difference between the cells 
physiologically? From your own observations do 
you think there is any correlation between the struc- 
ture of cells and their function? Explain clearly. 

5. Is there any evidence in Spirogyra of a correlation 
between structure and env ronment? Explain. 

D. Asexual Reproduction in Spirogyra: 

I. From what you have already learned of Spirogyra, 
state the possibilities of vegetative propagation in 
this plant. 

E. Sexual Reproduction in Spirogyra: 

1. Use fresh material, if possible; otherwise preserved 
specimens, or prepared slides. 

2. Observe the various stages in the fusion of two cells 
(gametes). Do the fusing gametes belong to the 
same, or to different filaments? Observe the 
conjugation-tubes connecting adjacent filaments.^ 
What is their function? Their relative diameter? 
Try to find tubes in various stages of formation. 
Are their distal ends open before they come into 
contact? How is the opening made? Do the tubes 
grow together or merely touch each other? 

3. Does conjugation seem to be a function of all the 
cells of the filament, or of certain cells only? 

4. Do the gametes pass from either filament to the 
other, or do the cells of a given filament all behave 
alike in this respect? In this connection see 
whether all the zygospores occur in one filament, 
or not. 

^ The form of conjugation described in the outline above, is termed 
" scalarif orm " (ladder-like). Another type, known as "lateral" con- 
jugation may frequently be met with, in which the gametes are formed by 
adjacent cells of the same filament. In less frequent cases the protoplast 
of a single cell organizes itself into a reproductive body (aplanospore) 
without conjugation. This process is a type of parthenogenesis. 



Io8 MORPHOLOGY AND LIFE HISTORY 

5. Does the cell-wall of the receiving cell serve as the 
cell- wall of the zygospore, or does the latter form a 
new wall? 

6. In a sentence define the term suppljdng cell, using 
the words gamete and conjugation. 

7. If fresh material is studied, describe any observed 
differences in color between the mature zygospore 
and the non-conjugating cells; any structural dif- 
ferences between the cells of a supplying filament 
and those of a recei\'ing filament. Do you observe 
any e\ddence of sexual differentiation in the 
filaments ? 

8. Explain whether Spirogyra represents a condition 
of isogamy or of heterogamy. 

9. Make drawings of all the following features shown 
by your material, with each cell about 50 mm. long. 
{a) Two adjacent cells in w^hich the conjugation- 
tubes are just beginning to develop. 

ijb) Two adjacent cells in which the conjugation- 
tubes have just met. 
{c) Two adjacent cells in which the active (supply- 
ing) gamete is passing through the conjugation- 
tube. 
{d) Two adjacent cells in which the passage is 

complete. 
{e) Two adjacent cells after conjugation is com- 
plete. Show carefully and accurately the details 
of structure of the zygospore. 
10. Study stages in the germination of the zygospore 
as shown on the chart. State, in order, the proc- 
esses that take place in the formation of the 
new plant (mature zygote) from the zygospore. 
Compare the plant of the new generation with 
its parents. 



SPIROGYRA SP. 109 

11. Is there a physiological division of labor in this 
plant? Explain in detail. 

12. Draw a diagram showing the ancestors of a plant 

of Spirogyra for three generations. 

13. To complete your notes on Spirogyra, write, at 
home, and before the next laboratory period, as 
clear and well -worded an account as you can of 
the life history of the plant. 

14. Arrange ferns, algae, mosses, liverworts, in a 
vertical column in the order of the complexity of 
their organization, placing the more highly organ- 
ized near the top of the column. Write a clear 
statement of the reasons for your arrangement 
of the above classes. 



Pleurococcus vulgaris (Green slime) 

A. Classification: 
Division I. Thallophyta. 

Subdivision I. Algae. 

Class II. Chlorophyceae (green algae). 
Order. Ulotrichales. 

Family. Chaetophoraceae. 
Genus. Pleurococcus. 
Species, vulgaris Menegh. 

B. Habitat: 

I. From the material given you, infer where this plant 
grows. Leave a blank space in your note-book, 
and before the next laboratory period, record further 
observations on this point, made out of doors, 
noting especially the following points. Does the 
plant appear to be more abundant on one side of 
the object on which it grows than on another? 
Describe and explain. In general, what external 
conditions seem to favor its growth? Do you ever 
find it intimately associated with other plants? 
Describe. 

C. Naked-eye Characters: 

I. Describe the color of a colony of Pleurococcus. 
Can you distinguish the shape or other characters 
of an individual plant? 

D. Microscopic Characters: 

I. With the needle carefully scrape off a bit of the 
plant from a piece of moist bark or wood, and 
mount it in water. 

no 



PLEUROCOCCUS VULGARIS III 

■V ■ 

2. Is the body of this plant differentiated into root, 
stem, and leaves? Is it composed of cells? If so, 
of how many? Make a thorough study of this 
point before you answer and thoroughly cons'der 
how many cells you think are necessary in order to 
make one plant. State your opinion, with reasons. 
Compare the arrangement of the cells with those in 
Spirogyra. 

3. Describe the color and shape of individual cells. 
Descr be and account for any variations observed 
in the shape of the cells. 

4. Carefully describe all the cell-organs you can 
identify in this specimen. Name all the cell-organs 
you cannot find. How does the chlorophyll occur 
in the cell of Pleurococcus? If you find chloroplasts 
state how many, their location, and relative size. 

5. Make careful drawings showing all features so far 
as observed, with none of the cells less than 15 mm. 
in longest diameter. 

E. Physiology: 

1. How does Pleurococcu remain fixed to the sub- 
stratum on which it grows? Are there special 
organs for this purpose? 

2. Are there special organs for the taking in of nourish- 
^ment from the substratum? How can the plant 

accomplish this process? 

3. Is photosynthesis possible with Pleurococcus? Give 
reasons for your answer. Are stomata present? 
Why? Describe how CO2 can be taken into the 
cell. 

4. Are there any special organs of respiration? How 
can this process take place? 

5. Do you think Pleurococcus is sensitive to stimuli 
from without? Give reasons for your answer. 



112 MORPHOLOGY AND LIFE HISTORY 

F. Reproduction: 

1. Do you find any cells that appear to be dividing? 
If so, carefully describe their appearance. What 
are the indications that a cell is dividing? 

2. Do the cells tend to remain united after cell divi- 
sion? Is this true of all of them? Describe. 

3. Make three diagrams, showing {a) the life cycle of a 
Pleurococcus plant; ijb) the descendants of one plant 
for six generations; (c) the ancestors of one plant for 
six generations. 

4. Is there a division of physiological labor in this 
plant, or are all life functions performed by every 
cell? 



Phycomyces nitens (or Rhizopus nigricans) 

A. Classification: 

Division I. Thallophyta. 
Subdivision B. Fungi. 

Class III. Phycomycetes (alga-fungi). 
Order. Mucorales (the molds). 
Family. Mucoraceae. 
Genus. Phycomyces. 
Species, nitens. 

B. Habitat: 

I. Upon what substratum is the Phycomyces growing? 
What atmospheric condition seems to be most 
favorable to its growth? 

C. Naked-eye Characters: 

1. Describe in detail the appearance of this plant as 
it grows. What is its color? Describe any varia- 
tions in color. 

2. Note the aerial filaments or hjrphae. Do they 
grow erect or horizontally? How many milli- 
meters long are they? 

3. On the ends of some of them observe the enlarged 
structure, the sporangium. Describe its shape. 
From its name, sporangium, what do you infer that 
it contains. Hyphae that bear sporangia are 
sporangiophores. What does the term literally 
mean? 

4. Compare the height of the sporangiophores bearing 
young (yellowish) sporangia, with that of those 
bearing more mature (dark-colored) sporangia. 
Explain the .significance and advantage of this. 

5. Using the hand lens, note the vegetative hyphae 

8 113 



114 MORPHOLOGY AND LIFE HISTORY 

that grow into the substratum (substance on which 
the fungus grows), and over its surface. These 
filaments constitute the mycelium. Compare their 
diameter mth that of the sporangiophores. Do 
they appear to branch? 
6. Make a drawing, illustrating all points observed. 
Make a diagram showing, in order, the relative 
heights of six sporangia of various ages. Indicate 
the scale used. 

D. Vegetative Propagation: 

1. If Rhizopus nigricans is used, study, with the naked 
eye, the formation of stolons by this plant, and 
describe in full, \\dth dramngs, this process of 
propagation. This plant (Rhizopus nigricans) was 
at one time called Mucor stolonifer. Explain the 
appropriateness of this latter specific name. The 
generic name, Rhizopus (root-like foot), refers to 
the branching myceUal h}^has, which form at the 
tips of the stolons. Explain the significance of the 
specific name nigricans (black). 

2. How does Phycomyces nitens increase vegetatively? 

3. Study and draw stages in the germination of spores 
that have been in sugar solution for twenty-four 
hours. (Use spores of Phycomyces or Sporodinia, 
as spores of Rhizopus do not germinate readily in 
sugar solution.) 

E. Microscopic Characters oj the Mycelium: 

1. Mount in water a small portion of the substratum 
with the mold attached, and, if necessary, very 
carefully tease it out mth the needles. 

2. Study the mycelium. Is it branched? Are the 
mycelial h^'phae of the same diameter throughout? 
Are cross-walls present? If so, describe their 
frequency. 



■* PHYCOMYCES NITENS II5 

3. Make a drawing to illustrate the above points. 

F. Physiology: 

1. Describe the color of the sporangiophore and 
sporangium as seen under the microscope, and state 
whether this color is in the cell-wall or in the cell- 
contents. 

2. If you detect any motion of the protoplasm (best 
seen in young sporangiophores) describe it accu- 
rately. Is it a true circulation {i.e., in various 
directions in a closed circuit), a rotation (i.e., up 
one side of the filament and down the other), 
or a streaming {i.e., all currents apparently toward 
one and the same end of the filament). Suggest 
any advantage this motion would be in the nourish- 
ing of the plant; in the formation of sporangia. 

3. Make a drawing of a portion of the hypha, at least 
15 mm. wide, showing the appearance of the con- 
tents, and. with arrows, the direction of motion. 

4. What foods does this fungus need? From where 
must they be obtained? Are they soluble? Can 
Phycomyces take in solid food? What process is 
necessary in our own bodies before we can utilize 
solid food? Must Phycomyces perform a like 
function? Is there a special organ for such a 
function? Must the process go on inside or out- 
side of the body of the plant? Why? 

5. Is photosynthesis possible with P/j3;(;owyc65.? Why? 
How must it get its carbohydrates? 

6. Does Phycomyces respire? Give a reason for your 
answer. 

7. What is the most obvious and important difference 
between the cells of Phycomyces and of Spirogyra? 

G. Asexual Reproduction: 

I. Study a sporangiophore. Is it of the same diameter 



Il6 MORPHOLOGY AXD LIFE HISTORY 

throughout? Are cross-walls an}'where present? 
If 50; describe their location. 

2. Is the sporangium borne on the tip of the sporangio- 
phore, or at one side? Aire its contents separated 
from those of the sporangiophore ? If so, how? 
Compare, on this point, young and old sporangia. 
Is there more than one sporangium on a sporangio- 
phore? Within the waU of the sporangium observ'e 
the central columella, surrounded by the spores. 
Describe the shape of the columella. Aie the 
spores numerous or few within one sporangium? 
Look for cases where the wall of the sporangium, 
has ruptured, and the spores are mostly scattered, 
leading the columella naked. 

3. Illustrate by drawings all features obser^'ed under 
Gj I and 2. Make the sporangium at least 20 mm. 
in diameter. 

4. Describe the shape, relative size, color, and surface 
markings (if any) of the spores. 

E. Sexual Reproduction: 

XoTE. — For this study Sporodinia may be substituted, 
as it more readily }-ields suitable material. 

1. Find conjugating branches. Describe their shape. 

2. Find mature conjugating branches with the end 
contents cut off to form gametes. The remainder 
of the branch is now called a suspensor. 

3. Find, on still more mature material, the gametes 
fused. 'UTiat is the resulting structure called? 
Describe its appearance. If the material is suitable, 
describe the germination of this structure. 

4. Illustrate with a drawing aU features observed 
under E. Make the suspensors at least 25 mm. 
long, and other structures in proportion. 



Saprolegnia (Water mold) 

A. Classification: 

Division I. Thallophyta. 
Subdivision B. Fungi. 
Class III. Phycomycetes. 
Order. Saprolegniales. 
Family. Saprolegniaceae. 
Genus. Saprolegnia. 
Species, sp. (^*.e., not given). 

B. Habitat: 

I. The spores of this fungus are widely distributed, 
and develop readily under suitable conditions. 
Such conditions are realized when a dead fly is 
placed in a dish of tap-water. The fungus will be 
sufhciently developed for study within five to seven 
days. 

C. Naked-eye Characters: 

1. Carefully observe the aerial hyphae as they grow, 
forming a halo about the body of the fly. What is 
the diameter of the halo? Its shape? Does its 
shape seem to be influenced by the shape of the fly's 
body? Do the filaments grow vertically upward 
and downward or only horizontally? What is the 
color of the halo? 

2. Estimate the average length of the hyphae. 

3. Can you detect any evidences of the formation of 
sporangia at the tips of some of the hyphae, and of 
sexual reproductive organs near the body of the fly? 
Use a hand lens if necessary. 

117 



ii8 



m:2^ 



:-Y A:?fD lUE HISTORY 



4. Make a diawmg, abofat 25 nmi. in knigest ^ineter, 
sboidng tiie a^yearance of this fangns as it grows <m 
die bo^ of the Jfy. 
Z>. Muanncopic Ciaracters: 

1. ¥rah die needle ch* scaJ^pdL caiefulfy remove a fe^ 
laments and mofont them in water. E:saniiiie 
"ai : L :.i e low power. 

2. Mile ;i.:t:-I coFwipaTisons of die tiqps of hjplis 
trJirrei :: : ::n spcNcan^ with those not thus 
n iiit i Its: e Jie appeaiance of the omtents 



3. D: y:--i-7 :::;; 

of a'vcge::::'t ilint: 
JR. Nmhitwmc : 

I. Seeif jc u ::i z:ii i ;~ 

n so, dc :_ zr_i iit 

in lengtl ~ :i:r_ :Jit 

tisite ttii ; - : ; ; i : 
2- Whcfc-c :-r tre 1 

Desoibe : 1 1 i v " ur t 

bodf. How c^i :- 1 ; 

the intezioi' of : it z ; 

3. Upon what doei -'zis :ii,r^^ itti: Sz3.ze in detail 
thenecessaijsteis ir_ z'lz ;:: : ess of getting this food 
into the intedc : : : It n; : eli .zi. In- thb connec- 
tion make comi iri : -i - : Ji .." jflrjncer (see F, 4, 
imder Pit y o iw ycey, p. 115). 

4. Is theie any condation heie between the absence of 
chkHOfdiyll and :le 11'::: it of the {dant? If so, 
e—'iLi and c:r_iii:t "i i_ P^ycomyces, and with 



"s in the fikunents? 
?!i5::is? Xudd? 
:'lz ii7rir3,nce of the tip 

:: rm m iiaiseter). 

'zti:iz.z enicy sporangia. 
1 - i. continuing its growth 
11; spoiangiinn? IIliis- 

i]- i: c —Tcelitnn) grow? 



SAPROLEGNIA IIQ 

F. Asexual Reproduction: 

1. Carefully study again the terminal sporangia. 
How many times longer than broad are they? 
Compare the thickness of the sporangium walls 
with those of the remainder of the hyphae. Can 
you detect any variations in the thickness of the 
sporangium walls? If so, describe and explain. 
Describe and account for the shape of the free tip 
of the sporangium. 

2. Describe the shape of the zoospores, or swarm- 
spores; their size; number in one sporangium; 
color. Are they all alike in these characters? 

3. Endeavor to find swarm-spores escaping from a 
sporangium. Do they merely float away, or have 
they power of locomotion? Look for organs of 
locomotion? If you find them, describe their 
number, length, action, and general appearance. 
Do they precede or follow the zoospore as it moves 
through the water? 

4. Do the zoospores ever move up or down through 
the water so as to be out of focus? If so, consider 
thoughtfully the thickness of the film of water 
in which they are, and try to form some conception 
of the size of a body that moves vertically beyond 
the range of vision in a film of such a depth. Briefly 
discuss this point. 

5. Do you see any evidence that any two of these 
swarm-spores are in the process of fusion? Do 
their movements appear to be directed, or not? 

6. Make suitable drawings to illustrate all points 
observed under F. 

G, Sexual Reproduction: 

I. Under suitable conditions female reproductive 
organs, oogonia, develop on certain hyphae near the 



I20 m:j^h:i::-y .\>-d lite history 

body of the fly, and each oogoniimi develops a 
number of eggs. If ocgonia are found., describe 
them carefully as directed above F. i ) for sporangia, 
makhig suitable drawings. P: the; always occur 
at the end of the hypha that bears :iiem? 
2- The male reproductive organs are antheridial fila- 
ments, rT:~diig- either below the oogonia or on 
ai ;.i:f:i: d^ji.c.^ They are of smaller diameter 
:den :be iiv^d.c^. If you find these organs, care- 
fully describe :dt:r appearance, contents, size, and 
relation to the oogonia. Illustrate aU points ob- 
served with suitable i: a ^dn r s . 
H. Genend QitestUms: 

1. Do you find a physiological division of labor iq 
Saprolegma? If so, describe in detaiL 

2. State why you consider this plant higher or lower in 
in the scale of life than Phycomyces or Fucus. 

3. Describe all methods of dissemination of 5a^r^/^^«w 
that you can think of. 

^Tlie de¥clo|Miient of the ^g-cdl witboot feitilizatMm ii.e^ by par- 
ikemitgemaas) is mans usual dian fCTfilibBitTon in SapnUgma, so that fer- 
tiMzatiaii, or even antheridisl Saments, may be wanting. 



Albugo Candida^ (Blister blight) 

A. Classification: 
Division I. Thallophyta. 

Subdivision II. Fungi. 
Class V. Phycomycetes. 
Order. Peronosporales. 
Family. Peronosporaceae. 
Genus. Albugo. 
Species. Candida. 

B. Habitat: 

This fungus is parasitic on plants belonging to the 
mustard family (Cruciferae) . It causes the ** blister- 
blight," or " white rust," on the leaves and stems 
of the shepherd's purse (Capsella bursa-pastoris) 
and often on the radish. 

C. Naked-eye Characters: 

1. Describe the appearance (color, shape, size, etc.) 
of the blisters formed by this parasite on the host- 
plant. What organs of the host are affected? 

2. Make drawings, natural size, showing all the 
features observed. 

D. Microscopic Characters: 

1. Study cross-sections of the host-plant taken through 
one of the blisters. 

2. What causes the blisters? In what tissue or tissues 
of the host does the mycelium grow? 

E. Nutrition and Growth: 

1. In what form must carbon be supplied to this plant? 
Why? 

2. In thin sections look for absorbing organs (haus- 
toria), branching from the mycelium and penetrating 

1 Cystopus candidus (Pers.) Lev. 

121 



122 MORPHOLOGY AND LIFE HISTORY 

througli the cell- walls into the cells. ^ Describe 
their relative length, shape and general appearance. 
How far do they project uito the cells? WTiat do 
jou infer is the function of these organs? Suggest 
a way in which they might be able to pierce 
the cell- wall. What other function must they per- 
form besides the one you have already mentioned? 

3. WTiere and how does this plant digest its food? 
What foods does it need? Wliat is their source? 

4. Is there an}^ correlation between the absence of 
chlorophyll and the habitat of this plant? Explain, 
and compare with Phycomyces and Marchantia. 

5. !Make a drawing showing three cells of the host 
with the adjacent mycehum and the penetrating 
haustoria. 

F. Asexual Reproduction: 

1. Observe the chains of spores (cofiftfia, or conidio- 
spores). On what are they borne? Describe then- 
shape, color, size. Are they all of the same size? 
Which is the youngest conidium in a chain? Why 
do you think so ? Of how many cells is each conidium 
composed? Are they attached to each other? If 
so, how? 

2. Obser^^e the conidia-bearing hyphae (conidiopliofes). 
Describe their shape, and the appearance <rf their 
contents. Do they have cross-walls? OI>serve 
this last point carefully, and describe. 

3. Describe in detail, from your own observations, 
the method of formation of the conidia. 

4. Make one drawing showing all points observed, 
including the tissues of both host and parasite. 

5. Make a second drawing of two conidiophores, 

1 The haustoria are difficult to identify, especially with poor sections, 
and too much time should not be spent in trying to detect them. 



ALBUGO CANDIDA 1 23 

showing the attached chains of conidia and the mode 
of formation of the latter. In this drawing make 
the conidia at least 5 mm. in diameter. 
6. Include in your notes at this point a brief descrip- 
tion of the germination of the conidia. (The infor- 
mation should, if possible, be obtained from 
material suppHed by the instructor, otherwise from 
lecture or reading.) 
G. Sexual Reproduction: 

1. The sexual reproduction of Albugo generally occurs 
in other parts of the host-plant, and later in the 
season than the asexual reproduction. The tissues 
of the host-plant containing the sexual organs of the 
parasite are generally enlarged (hypertrophied) and 
distorted. 

2. In the material given you observe the large spherical 
oogonium, containing a single oosphere or egg 
surrounded by the so-called periplasm or epiplasm. 
Is the oogom'um sessile or stalked? 

Closely appressed to the oogonium at some point 
find the smaller antheridium. Describe its shape, 
and general appearance. Are its contents separated 
from those of the hypha by a cross- wall? 

4. How does the male gamete fsperm) pass through 
the oogonium- wall and periplasm to the egg? 

5. If your material is suitable, observe and describe 
the mature fertihzed egg (oosperm). After fertili- 
zation the periplasm becomes transformed into the 
wall of the oosperm. Note the exospore (of one 
layer) and the endospore of three layers. 

6. Make drawings showing all features observed un- 
der G, 

H. General Questions: 

I. Explain how Albugo is disseminated. 



124 MORPHOLOGY AND LIFE HISTORY 

2. What weather conditions would favor its dissemina- 
tion? 

3. The blight caused by Albugo is difficult to eradicate. 
What characteristic of the plant helps to explain 
this fact? 

4. Classify the Phycomycetes you have studied as 
either Zygomycetes (Section i), or Oomycetes (Sec- 
tion 2), and give a reason for your classification. 
Give the literal meaning of these two new terms. 



Agaricus campestris (Meadow-mushroom) ^ 

A. Classification: 
Division I. Thailophyta. 

Subdivision B. Fungi. 
Class V. Basidiomycetes. 

Series. Eubasidiomycetes (true or typical Basi- 
diomycetes) . 

Sub-class. Hymenomycetes. 
Order. Agaricales. 
Family. Agaricaceae. 
Genus. Agaricus. 
Species, campestris. 

B. Habitat: 

I. From your own observation, and from the class 
discussion and assigned readings, describe the 
habitat of this plant. 

C. Naked-eye Characters: 

1. Form. — Describe the form of your specimen. If 
specimens of different ages are available, compare 
their forms and describe any variations in specimens 
of various ages. Is the form of the mature speci- 
men constant? Is its size constant? 

2. Color. — Describe accurately, noting especially any 
variations in color. 

3. Structure. — Note the differentiation of the plant- 
body (thallus) into an expanded portion (pileus), 

1 The outline for the study of a fleshy fungus has been prepared with 
special reference to the meadow mushroom (Agaricus campestris). It is 
general enough, however, with the exception of the outline of classifica- 
tion, to apply to any gill-bearing form. Indicate in your notes the exact 
genus and species given you for study. 

I2S 



126 MORPHOLOGY AND LIFE HISTORY 

borne on a stalk or stipe. Is there a ring of tissue 

(aimulus) around the stipe? 

(a) The pileus. Describe the shape, size, color, 
and any characteristic markings on its upper 
surface. Examine carefully and describe the 
margin of the pileus. Are there any charac- 
teristic elevations or depressions on the pileus? 
If so, state how many and where they are. 
Compare the color of the under surface in young 
and old specimens. 

Describe the shape, arrangement, relative 
number and color of the lamellae, or gills. 
Are the margins (free edges) of the gills entire 
or notched? Do they extend clear to the stipe? 
Are they attached to the latter? Do they all 
extend clear to the margin of the pileus? 
Describe any variations in size. Count the 
gills in a space of lo mm., then calculate from 
the circumference of the pileus the total number 
of gills. 

{b) The stipe. Describe its shape, and color, and 
any variations in color and diameter. Describe 
its mode of attachment to the pileus. De- 
scribe the method of attachment of the plant 
to the substratum. Is there a mycelium or 
other special means of fixation? If so, is it 
, continuous with the tissues of the stipe? 

(c) The amiulus. If an annulus is present, de- 
scribe its location on the stipe; its structure. 
Compare its structure with that of the mem- 
brane on the edge of the pileus. What is the 
relation between the membrane and the annulus 
in young specimens? When these structures 
are united they form a veil. Is a veil present 



AGARICUS CAMPESTRIS 1 27 

in young specimens examined by you? What 
do the annulus and marginal membrane repre- 
sent? 
(d) Make drawings, not less than life size, of both a 
young and a mature specimen, as seen from the 
side, labeling all parts. 
{e) With a sharp scalpel or razor carefully divide 
your specimen longitudinally through the 
middle, and make a drawing illustrating all 
features shown in longitudinal sectional view. 
(/") Make a third drawing showing the structure 
and outline of the stipe as seen in cross-section, 
and a fourth drawing, showing the outline of the 
gill as seen in cross-section. 
D. Microscopic Characters: 

I. When suitable material is available, note and de- 
scribe the mycelium, extending through the soil. 
2. The annulus and stipe. Mount (in clearing fluid 
or water) thin longitudinal sections passing through 
the stipe. Is the stipe composed of distinct tissues, 
e.g., like the hypocotyl of Ricinus, or the thallusof 
Fucus? If so, describe. Observe that the stipe is 
composed of hyphae. Of what is the annulus 
composed, and what is its relation to the tissue of 
the stipe? Do the hyphae have cross-walls or 
septa? If so, what angle do the septa make with 
the walls of the hyphae? Do the hyphae branch? 
Do you find spaces between the hyphae? If 
so, describe their size and distribution. Make a 
drawing to show the features observed under 2. 
3. The pileus. Mount (in clearing fluid) a thin longi- 
tudinal section passing through the stipe, pileus, and 
a portion of a gill. Examine under low power. 
Can you trace the hyphae of the stipe into the pileus? 



uS JBLil_? 



:.r 'in. dlEL: 



^ JJQ£X; 






4- 



.k m 



AGARICUS COMPESTRIS 120 

in the morning. Study a spore-print of this species, 
describe it fully and state how it was formed. 

5. Make accurate drawings showing all features ob- 
served under E, 2 and 3. 

6. Sexual reproduction is unknown among the fleshy 
fungi. 

7. Diagram the Hfe history of the species studied. 

F. Nutrition and Growth: 

1. Could the mushroom exist independently of other 
plants? Consider this question thoughtfully and 
answer as fully as possible in a well-worded para- 
graph. 

2. Suggest an explanation for the rapid growth of 
mushrooms. 

G. General Questions: 

1. State whether there is a division of physiological 
labor in this plant, and, if so, to what extent. 

2. In what ways may this plant become widely 
distributed? 

3. State, with reasons, whether you consider the mush- 
room a more or less highly developed plant than 
{a) Spirogyra; (b) Polypodium. 



r^J..C-ClIll£. ^Tf. . . ."T." i •'• jn-i.-.T .'.. . STf 






C::t: 



aond sfaUbe lii^iit plamls aie infEsted irafli f^^ 

Wbat is die sfgniikanc e of its ^eciz: zi.~t 

2. Pvcdmi grmmmds icquii.: e-s ?— : ^^?r?z : iiir. is 
basts in cnler to cxHnplf : t : : r __: t ;_ s . ; 
Acse is tihe bfinbecTf 5 -'t ;; Tit :i::t:: - 
sfage, buwuviai, Js not i:5':-_:r.;' z^^zzii. ::: in 
GCffain mgjkiiiSt, c^^ Ans :: i _ i : i t . 1 1 : : i., trstem 
Stales^ and C^fifacnia,'^it:t :'it :i::t:: i :es i:t 

nafiiffilly grow, tras s-^.gr n^. .z ._t 

fin^psbdn^padiapscsLrr.Ti .:.e "ii'.r: stiriz. 

on idnfter idieat, or i:5:.:/.- ly r:y:t.':aiii in 
grahij or cycnby iiredi~: isi irts 



C. Wmkeirtyt Chmmders: 

I. Stnfy tihe inferlBdi Inf of lOie badicny. On its 
under smfMse observe ±e i.r tr-cnqps c: scia 
(angii, jp< ium). 



^ PUCCINIA GRAMINIS I31 

2. On the upper surface observe the small dots, the 
pycnia (pycnidia, or spermatia). What is their 
color? Their shape? What relation does their 
position bear to that of the aecia? 

3. Study both aecia and pycnia with the aid of a hand 
lens. Describe carefully the appearance of the 
infected areas. 

4. Make a drawing, Hf e size, of the barberry leaf, show- 
ing the features under C, 1-3. 

D. Microscopic Characters: 

1. Study longitudinal sections through an aecium, 
using low power. 

2. How are the infested tissues of the host affected by 
the parasite? ^ 

3. Note the aeciospores. Describe their shape. Are 
they all of the same shape and size? How are they 
produced? What is the cause of the cluster-cups 
that appear on the leaf -surf ace? 

4. Make out all you can of the details of the mycelia, 
and their relation to the cells of the host-plant, and 
describe. 

5. Make a drawing of two aecia in different stages of 
development, one before the epidermis of the leaf 
has been ruptured. Make the aecium at least 
30 mm. in longest dimension. 

6. Make a study, similar to that outlined in D, 1-5, 
of the pycnia, as seen in longitudinal section. Ob- 
serve the slender thready and the minute spermatia. 

7. What is the function of the aeciospore? Of the 
pycnia? 

Uredo-stage (on Wheat, Triticum vulgare) 

E. Naked-eye Characters: 

I. Study the diseased spots on the leaves of the wheat. 



132 MORPHOLOGY AND LIFE HISTORY 

Use the hand lens, if necessan^, to make out the 
features clearly. 

2. Is the shape of the spots (sori, sing., sonis) uniform 
and characteristic? 

3. State their color. 

F, Microscopic Churacfers: 

1. Study longitudinal sections through a uredo-sorus. 
If the material is not fresh, remove some of the 
contents of the sorus with a needle, and mount in 
water. Study under high power. 

2. Describe the color, shape, and relative size of the 
cells. Are there any surface marks? Do you find 
any remnants of the pedicle to which the uredinio- 
spore was attached? What can you say of the 
thickness of the cell-wall? 

3. Of how many cells is the urediniospore composed? 

4. Make careful drawings of two or three uredinio- 
spores, at least 15 mm. in longest measure. 

5. State the function of the urediniospore. 

Tellax Stage (on \Mieat) 

G. Xaked-eye Characters: 

I. Study the telial sori, as directed under E, above. 
Describe the order of their distribution. 
H. Microscopic Characters: 

1. Study as directed under F, above. 

2. Include in your notes, at this point, a description 
of the germination of the teliospore (teleutospore). 
\Miat is its function? State the fimction of the 
basidium fpromycelium) , and of the spring-spores, 
or basidiospores (sporidia). 

/. General Questions: 

I. Wliat features seem to you to make this parasite 
easily distributed, and difficult to eradicate? 



PUCCINIA GRAMINIS 133 

2. State, with reasons, whether you would consider 
Puccinia graminis higher or lower in the scale of 
life than Vaucheria (or Fucus), and Albugo (or 
Mucor). 

3. Write a brief summary of the life history of Puccinia 
graminis, and devise a diagram to illustrate this. 



Note 

From the fern to the wheat rust we have studied plants 
in the descending order, from higher to lower in the scale. 

We now return to the ferns, taking the quill-wort 
{Isoetes), illustrating the Eusporangiatae. 

The systematic relationship of the Isoetaceae is doubt- 
ful. On the basis of certain structural features of the 
gametophyte {e.g., the structure of the archegonia, and 
the possession of multiciliate sperms), some botanists 
class them with the Pteridophyta. On the other hand, 
some features of the anatomy of the sporophyte {e.g., the 
possession of a ligule on the sporophyll) suggests that 
they are more closely related to Selaginella (Lepido- 
phyta). 



Isoetes ( Quill WOE.T) 

A. Classification: 

Di\ision in. Pteridopliyta. 
Class I. Eusporangiats. 
Older. Jaodtakss. 

Family. Tsoetaceas. 
Genus. Isoetes. 
Species, (e.g., lacustris.) 

B. Habitat: 

Some forms grow on the bottom of ponds, others in 
moist meadows, or on the margins of bodies of water. 

The Sporophyte 

C. Naked^ye Characters: 

1. General Features. 

(a) Note the differentiation of the plant into root 
and shoot, and of the shoot into stem and leaf. 

(h) Make a sketch, natural aze, showing the 
general appearance of the entire plant. 

2. The Stem: 

{a) Without removing any of the leaves or roots, 
ascertain all you can about the shape, siae, 
branching, and other characters of the stem, 
and describe. 

(h) With a sharp scalpel, make a cross-section of 
the stem through the middle, being careful not 
to remove any of the leaves or roots. 

(c) Describe the outline of the stem as seen in 
cross-section. Note the hm^tuBHt l furrows 
which give it a lobed appearance. 
134 



ISOETES 135 

(d) Are the roots attached to any special region of 
the stem? If so, describe. 

(e) Study the cross-section, identifying the central 
(vascular) cylinder, the epidermal layer, and, 
between the two, the fleshy tissue composed of 
several regions that are not distinguishable 
to the naked eye. 

(/) Make a drawing (X 3), showing the outline of 
the stem in cross-section, the tissue-regions 
observed, and the attachment of the roots. 

The Roots. 

(a) Describe the general appearance of a single root. 
Does it taper? Note that it is shghtly fleshy. 
Are the branches forked at the tip (dicho- 
tomous), or lateral? Dichotomous branching 
of roots is very rare. 

(b) Make a drawing (X 2) showing these features. 
The Leaves. 

(a) Carefully remove one of the outer leaves at its 
point of attachment to the stem, first noting 
carefully which is its inner (ventral) surface, 
and which is its outer (dorsal) surface. 

(6) State whether the leaf is sessile or petiolate. 
The end by which it is attached is the leaf- 
base and the remainder of the leaf is called the 
lamina or blade. Note that the blade is 
subulate (awl-shaped). 

(c) Describe the exact length of the leaf in milli- 
meters. Observe the sKght shallow groove or 
flattening. On which side of the leaf is it? 

id) Hold the leaf up to the light and observe the 
single vascular bundle, surrounded by air 
chambers separated into compartments by 
numerous diaphragms. 



136 MnSEHOI/OGY ANB UFE HISTOXY 

(e) Make a drawing (X 2) illiistraliiig liie features 

mentioned in 4, (c) and f^. 

(/) Make a cross-section of tiae Made near tiie 
middle, and note the number of air chamters 
surrounding tiie vascular bundle. 

{g) Make a diagram, 10 mm. in diameter, skowiiig 
the leaf-structure in cross-section. 

(h) On plants which grow under water no stomata 
occur, but tiie}^ are present on leaves that grow 
exposed to the air. Are stomata present in 
your specimen? If so, make a drawing of 
two or tliree, each 15 mm. in longest dBameter. 

(i) Study carefully tbe expanded base of thfe kai^ 
noting tke membranous margins. 

(J^) Directiy above the leaf-iosertioii, and on flie 
ventral (inner) surface, observe tbe csmty or 
pit (fovea);, containing tbe sin^ spoaDE^gpnm. 

(/) Note the thin membrane (vidniii) eactendGni^ 
over the sporangium. The velnm fe fomfted by 
the projection of tiie margin of the fovea. It is 
absent in some species, and in I. ',:-custns it 
does not completely cover the sporanghnn. 
In terrestrial species there is no opening througb 
it. State the shape and location of this open- 
ing in your specimen, using a hand lens for the 
observation. 

(m) Above the fovea find a flat, membranous out- 
growth, the ligule. Describe its shape and 
state toward which end of the leaf it projects. 
The slightiy swollen base of the ligule is in- 
serted in a depression (foveola) smaller than the 
fovea and directiy ab: ■ t :: This last point is 
not easily made out except with the aid of a 
hand lens or microscope. 



ISOETES 137 

(n) Make drawings as follows: 

(i) A leaf-base, 20 mm. at greatest breadth, 
showing all points observed under 4, 
iiy{m). 

(2) A diagram, 40 mm. in greatest width, of an 
imaginary cross-section, of the sporophyll, 
taken through the middle of the fovea. 

(3) A diagram, 15 mm. in greatest width, of 
an imaginary median longitudinal section 
through the base of a sporophyll. 

D. Asexual Reproduction: 

1. Note that some of the sporophylls bear large spores 
(megaspores) , and some small spores (microspores) . 
Study any constant differences {a) in structure, 
(b) in position on the stem, between the mega- 
sporophylls andthemicrosporophylls. Define each 
of these terms. 

2. How many megaspores does a megasporangium 
contain? 

3. Measure the diameter of a megaspore in millimeters. 
Study and describe its shape under the low power 
(mounted in water), noting any surface marks. 
Explain the presence of angles on the spore. 

4. Make a drawing of a megaspore, 20 mm. in diameter. 
Indicate the amount of enlargement. 

5. Study microspores under high power, describing 
their shape and surface marks. Draw two or three 
to the same scale as the drawing of the macro- 
spore. The number of microspores in /. echinospora 
is said to be from 150,000 to 300,000; of megaspores 
150 to 300. 

6. Why is Isoetes a heterosporus pteridophyte ? 
Compare it with Polypodium vulgare in this 
respect. 



138 MORPHOLOGY AND LIFE HISTORY 

THE GAMETOPHYTE 

The germination of the spores and the development 
of the male gametophyte from the microspore, and of the 
female gametophyte from the megaspore. are ver\' 
difficult to follow, and will be omitted here. The struc- 
tures of the gametophytes, and the process of sexual re- 
production should be carefully studied in a text-book, 
and demonstrated by the instructor, if material is available. 
E. Nutrition and Growth: 

1. Is the gametophyte at any stage dependent upon 
the sporophyte ? The sporophyte upon the game- 
tophyte? {Consult a text-book.) 

2. It is important to remember that: 

(a) Tlie microspore begins to germinat'e before it is 
set free, di\dding into two cells, a large one and 
a small one. The smaller cell constitutes the 
entire vegetative portion of the male gameto- 
phyte. The larger cell de^'elops into an an- 
theridium, consisting of four wall-cells, and four 
central cells. Each of the latter develops into 
a multicihate, spirally coiled sperm, resembling 
those of the true ferns. 

(6) The megaspore begi?is to germinate after if is set 
free. It never develops chlorophyU-bearing 
tissues. In germination the nucleus di\'ides 
into about 50 nuclei before any cells are formed. 
Then cells begin to be organized about the 
nuclei, forming a small-celled tissue in the apex 
of the spore (where the three ridges meet), 
and a larger-celled tissue below. .-Vrchegonia 
then develop in the small-celled tissue, and the 
larger-celled tissue serves to nourish the young 



ISOETES 139 

embryo-sporophyte, that develops from the 
fertilized egg. 

The archegonia are exposed for fertilization 
by the splitting of the wall of the megaspore 
along the ridges, but the prothallus itself does 
not project beyond the walls of the spore. 

When the sporophyte begins to develop from 
the fertilized egg, it continues to grow, without 
any resting period, until it is mature. 
Diagram the life cycle of Isoetes, as directed for 
Marchantia. Let MG = male gametophyte; FG — 
female gametophyte; s = sperm; e — egg; S = 
sporophyte; mi = microspore; mg = megaspore. 



Equisetum (Horsetail) 

A. Classification: 

Division IV. Calamophyta. 
Class II. Eqmsetineae. 
Order. Equisetales. 
Family. Equisetaceae. 
Genus. Equisetum. 
Species, (e.g.) arvense. 

B. Habitat: 

I. The field horsetail {E. arvense), is common along 
railway embankments, roadsides and fields. It 
apparently prefers north-facing slopes, and has a 
great tendency to become weedy. 

C. Naked-eye Characters: 
I. The Stem. 

(a) Using herbarium specimens or alcoholic material, 
if fresh material is not available, observe the 
underground stem (rhizome), and the upright 
aerial branches. 

{b) Of the latter, observe two kinds; (i) non-green, 
unbranched, bearing only scale leaves, and 
terminating in a prominent strobilus or cone; 
(2) green_and branched, bearing leaves, but 
no cone. 

(c) Which kind of aerial branch appears first above 
ground in the spring ? What advantage may this 
possess for the species? 

(d) Explain the physiological significance of the 
green color of the non-reproductive branches. 

140 



EQUISETUM 141 

Of what significance, in this connection, is their 
profuse branching? 

(e) Describe the surface of the stem along the 
internodes, noting the presence or absence of 
ridges, the hardness (or otherwise), and the 
"feel" of the surface. To what are the last 
two characters due? 

(/) If material of Equisetum hyemale (the '^ scour- 
ing rush") is available, it will be instructive to 
burn a portion of the stem in a Bunsen flame, 
and to examine the unburned portion under 
a microscope. The preservation of the cell- 
walls, uninjured by the flame, is due to the 
fact that they are impregnated with silica, 
taken up by the plant from the soil in the 
form of a silicate, and secreted by the proto- 
plasm of each individual cell. It is the pres- 
ence of the silica that made this species useful 
for scouring cooking utensils, and thus gave it 
its common name. 

2. The Leaves. 

(a) Describe the shape and character of the leaves; 
their arrangement on the stem {i.e.j opposite, 
alternate, or whorled). 

(b) Do the leaves function in the work of photo- 
synthesis? In what organ or organs is that 
function performed? 

(c) To what, in the fern, are the branches of the 
vegetative part of the stem analogous? To 
what are they homologous? To what, in the 
fern, are the scales at the nodes analogous? 
To what are they homologous? Explain. 

3. The Roots. 

(a) Briefly describe their character and distribu- 



142 MORPHOLOGY AND LIFE HISTORY 

tion. Does their distribution on the rhizome 
bear any constant relation to the point of origin 
of the aerial branches? 
4. Make drawings showing all points observed under 

C, 1-3- 
D. Asexual Reproduction: 

1. Vegetative Propagation. 

(a) Describe the possibility of the multiplication 
of new individuals by isolating pieces of the 
rhizome. 

2. Reproduction by Spores. 

{a) Sketch the strobilus or cone (X 3). 

(b) Make a cross-section of the cone at about one- 
third of the distance from the apex, and observe 
the central axis, and the manner in which the 
sporophylls are borne. 

{c) Carefully dissect off a sporophyll, and observe 
(i) its stalk; (2) its peltate (shield-like) top; 
(3) hanging from the under surface of the 
shield, the sporangia. How many sporangia 
on each sporophyll? Examine several sporo- 
phylls to see if the number of sporangia is 
constant. Describe the dehiscence of the 
sporangia. 

(d) Examine the spores under the microscope. 
Can you detect more than one size; i.e., is 
Equisetum a homosporus or a heterosporus 
plant? 

(e) Describe the appendages (elaters), of the 
spores. How many on each spore? They are 
formed by a modification of the outer coat of 
the spore. Observe their behavior when 
breathed on at frequent intervals. 

(/) While the spores are morphologically homo- 



^ . EQUISETUM 143 

sporous, they give rise to dioecious gameto- 
phytes. Are they, therefore, physiologically 
ahke? 

(g) Since the spores have different sex-value, some 
giving rise to antheridial, others to archegonial 
prothallia, suggest the advantage of the hygro- 
scopic elaters in tending to tangle up together 
several spores before they germinate. 

(h) Make drawings illustrating all points observed 
under Z), 2, («)-(/). 

E. Sexual Reproduction: 

1. It is not essential, in an introductory course to 
study the gametophytes, and sexual reproduction 
of Equisetunij and it is seldom possible to secure 
suitable material in sufficient quantity for a large 
class. 

2. If material is abundant and time permits, the 
gametophytes may be studied, described, and 
sketched, noting especially color and general form, 
branching, rhizoids, archegonia, antheridia, and 
the dioecious habit. 

3. From prepared slides further details as to arche- 
gonia, antheridia, eggs, sperms, and fertilization 
may be studied, under the instructor's direction. 

F. Division of Physiological Labor: 

I. Write two or three paragraphs describing the 
division of physiological labor, (a) as between 
various vegetative processes, and ih) between the 
latter and reproductive processes. Give special 
attention in this to the work of each of the three 
kinds of branches. 

G. Life Cycle: 

I. Make a diagram, as previously for other forms, 
illustrating the life cycle of Equisetum, 



Lycopodium (Club-moss) 

A. Classification: 

Division V. Lepidophyta. 
Class I. Lycopodineae. 
Order. Lycopodiales. 
Family. Lycopodiacese. 
Genus. Lycopodium. 
Species, (e.g., clavatum.) 

B. Habitat: 

I. Nearly all the species of Lycopodium prefer moist 
situations, and one or two of them are aquatic. 
They are widely distributed over the earth, in both 
hemispheres, from the torrid to the frigid zones, 
and commonly grow in shady or partly shaded 
places. Lycopodium Selago and a few other species 
are epiphytic. They all prefer a substratum rich 
in humus or other organic matter. 

TEE SPOROPHYTE 

C. Naked-eye Characters: 

1. General Features. 

(a) Note whether, or not, the plant is differentiated 
into root and shoot, and the latter into stem 
and leaves. If the stem branches, briefly 
describe. 

2. The Stem. 

{a) Describe the attitude of the stem (e.g., erect, 
trailing). Does the tip of the stem turn up, 

or otherwise? 

144 



^ LYCOPODIUM 145 

(b) Describe the mode of btanching. 

(c) Are there any specialized (e.g., cone-bearing) 
branches? 

(d) Is there a terminal bud? Lateral, or axillary- 
buds? 

3. The Roots. 

(a) Does the stem bear roots only at its posterior 
end, or otherwise? Describe. 

(b) Briefly characterize the roots. 

4. The Leaves. 

{a) State their manner of distribution on the stem. 
{b) Describe an individual leaf. 

5. Make drawings as follows: (i) of a portion of the 
stem, to show mode of branching, distribution of 
leaves and roots, and other general features, natural 
size; (2) a leaf (X 5). 

D. Asexual Reproduction: 

1. Vegetative Propagation. 

(a) Describe the method of propagation by the 
annual apical growth of the stem. 

(&) Does the species you are studying in the 
laboratory possess buds or bulbils that may 
fall away, and develop into new plants? If so, 
describe their distribution on the stem; their 
relation to leaves, etc. 

2. Reproduction by Spores. 

(a) Describe the location of sporangia, especially 
their relation to leaves. Are they borne in the 
leaf -axils or on the leaf-surface? If the latter, 
on which surface? What relation do they bear 
to the leaf -base? Is there more than one 
sporangium to each leaf? 

(&) Are there special sporophylls? If so, how do 

they differ in location and characteristics 
10 



146 MORPHOLOGY AND LIFE HISTORY 

from the foliage-leaves? Are they aggregated 
in a cone? If so, what effect does the forma- 
tion of the cone have on the further growth of 
the branch? 

(<:) Is Lycopodium a Jwmosporus or a hekrosparus 
plant? 

{d) Describe a single sporangium, its mode of 
dehiscence, and the relative number (i.e., 
few or many) of spores it bears. 

(e) Into what do the spores develop? 

(/) Make dra-^ings as follows: (i) a cone (X 4); 
(2) a sporophyll, with sporangium (X 10); (3) 
under the low power a few of the spores, and 
(from younger sporangia) a few of the spore- 
tetrads. 

THE GAMETOPHYTE 

E. Sexual Reproduction: 

1. The gametophyte of Lycopodium is rarely seen, and 
not readily obtained in artificial culture. Its 
laboratory study may be omitted in a beginning 
course, but the subject should be presented by 
lecture, or preferably studied from a text and then 
discussed in class, vi-ith demonstrations of preserved 
material. 

2. Diagram the life cycle of Lycopodium. 



Selaginella (Little club-moss) 

A. Classification: 

Division V. Lepidophyta. 
Class I]. Lepidodendrineae. 
Order. Selaginellales. 
Family. Selaginellaceae. 
Genus. Selaginella. 
Species, sp. (Any available species may 
be used.) 

B. Habitat: 

I. Various species of Selaginella are common in cul- 
tivation in greenhouses. In nature they usually 
grow in moist situations, usually preferring shade. 

THE SPOROPHYTE 

C. Naked-eye Characters: 

1. General Features, 

(a) If possible, observe plants of various species 
growing in greenhouses, noting their general 
appearance and habit {e.g.j erect, climbing, 
trailing). 

2. The Stem, 

(a) By breaking off a small piece from the end of 
your specimen, ascertain whether the stem is 
tough, brittle, fibrous, etc. 

(b) Describe the mode of branching (e.g., alternate, 
opposite, dichotomous (forked), etc.). Do the 
branches bear any relation to the leaves, e.g., 
are they in leaf -axils? 

147 



148 ii:ijz: :::■■. o" izrz zii::i-'' 



«/ — 



oi^ht? 



etc? 
(f^ Dcaciflie aMty ainianMifc 



(0 Besdiiie wf ^uuIub m ti^ cnkr of Ok 

fo aniwiitl iarit. 



3. TtmRmis. 

(1) Do Ik : : :i 1 1 If so^ descdbrL 



(c) Aic ttkf 



Ji y. M 7 __ 1.2^ tibcnr Inratiwij 



(A USaikt 



rifCXiB 



iixii^. 



SELAGINELLA 1 49 

scope, using low and high powers, and describe 
all details of leaf-structure thus brought out, 
including 

(b) The shape and arrangement of the cells; the 
color, size, and distribution of the plastids in 
the cells; any other cell contents; 

(c) Variations between marginal cells, those along 
the central axis, and those lying between. 
Account for any constant differences observed. 
Do you think any observed differences may be 
attributed to environment? Explain. 

(d) Can you identify a tiny, membranous flap, 
the ligule, near the leaf-base? On which side 
of the leaf (dorsal or ventral) is it? Be sure 
to examine both sides of the leaf in this connection. 

(e) Are there stomata? If so, describe their 
location. 

(/") Make drawings sufficiently large to illustrate 
all points observed under D. 
2. The Stem. 

(a) With the razor, make thin cross-sections of 
the stem, and mount them in water or clearing 
fluid. 

(b) Is the stem differentiated into (i) epidermis; 
(2) vascular regions; (3) fundamental tissue 
(cortex)? If so, describe. 

(c) Note the presence or absence of air-spaces. 

(d) Compare the tissue-system of the Selaginella 
f stem with those in the fern. 

(e) Describe the distribution of xylem and phloem 
in the vascular bundle. 

if) Do you find indications of vascular bundles 
passing out to the leaves? 



150 MORPHOLOGY AND LIFE HISTORY 

{£} Draw a section of the stem (X 20), to illustrate 
2, {a)-{c). 
E. Asexual Reproduction: 

1. Vegetative Propagation. 

{a) Describe any means of vegetative propagation 
disclosed by your observations, already made. 

(h) If opportunity offers, the vegetative propaga- 
tion of Selaginella may be experimentally 
demonstrated in the greenhouse or Wardian 
case. 

2. Reproduction by Spores. 

(a) Observe the ''cones." How are they dis- 
tinguished? Are they ter mi nal on the main 
branches, or axillary? 

(b) Draw (X 5)- 

(c) Place a small portion of a branch, bearing several 
mature cones, under a glass bell-jar, and after 
twenty-four to forty-eight hours observe the 
distance to which the spores have been projected. 
Note the two kinds, their relative number, and 
differences in color, etc, 

(d) Carefully remove sporophylls (i) from near the 
base of the cone; (2) from the middle or above, 
and mount in water or clearing fluid, keeping 
distinct, on separate slides, those from the two 
regions. 

(e) Note both megasporophyUs, bearing mega- 
sporangia, and microsporophylls bearing micro- 
sporangia. How are they distinguished? 

(f) Are the sporangia inserted on the leaf, or on 
the stem in the axil of the leaf? Compare with 
the other plants studied in this respect* 

(g) Describe the structure of the walls of the 
sporangia. 



SELAGINELLA 151 

> ■ 

Qi) Carefully count and record the number of 
megaspores in one megasporangium. Is the 
number always even? 

ij) Carefully observe the megaspores under a high 
power, and endeavor to account for their shape. 

(j) Make drawings to show all points observed 
under E, 2, {a)-{h). 

(k) Make a study of the microsporophylls, micro- 
sporangia, and microspores, similar to those 
just made under E, 2, (a)-{i). 

(I) The number of microscopes is too large to 
permit of their being readily counted. Sug- 
gest any advantage to the plant in such a large 
number of microspores. Explain the cause of 
the difference in size. Suggest an advantage 
to the plant in the large size of the megaspore. 
(m) Mount megaspores and microspores together 
and make drawings to show their relative 
sizes. 
(n) Make drawings to illustrate all points observed 
under E, 2, (k). 

F. Sexual Reproduction: 

I. The gametophytes of Selaginella are not readily 
obtained in suitable form for study. If prepared 
slides are available, studies may be made of: 

(a) Archegonia and eggs. 

(b) Antheridia and sperms. 

G. Comparisons: 

1. Compare the relative prominence of the gameto- 
phyte and sporophyte in Selaginella. Compare, 
in this respect with all the forms previously studied. 

2. Compare the method of reproduction by spores in 
Selaginella with that in the forms previously 
studied. Why should Selaginella be considered 



152 MOSFHDLOGY AND LIFE HISTORY 

either higher or lower in the sc^e of life than 
those forms? 
H, L^e Cyde: 

I. Make a diagram to iDiistrate the life cyde of 
Sdagm^a. Briefly state difiEerences Ibetween this 
life history and that of the fern, and of Antkoceros. 



Zamia floridana (A cycad) 

A. Classification: 

Division VI. Cycadophyta (The Cycads). 
Class II. Cycadineae (Modern Cycads). 
Order. Cycadales. 
Family. Cycadaceae.^ 
Genus. Zamia. 
Species, floridana. 

B. Habitat: 

I. Most of the Cycadales occur only within the tropics, 
but two genera, Zamia and Cycas^ are subtropical. 
Zamia occurs in the United States only in Florida, 
where it is rather common. It is frequently culti- 
vated in greenhouses. 

VEGETATIVE ORGANS 

C. The Stem: 

I. Briefly describe the stem, noting its general appear- 
ance, size, relation between its diameter and height, 
variations in diameter, character of the surface, its 
relation to the surface of the soil. Note the pres- 
ence or absence of branches. 

D. The Leaves: 

I. Describe their arrangement on the stem, the nature 
of the blade (entire, divided, etc.), the color, and 

1 By some botanists the genera Zamia, Macrozamia, and Dioon, having 
both staminate and carpellate cones, are assigned to a separate family 
(Zamiaceae), distinguished from the Cycadaceae (in the narrower sense), 
which bear only the microsphorophylls in cones. 

153 



154 MORPHOLOGY AXD LIFE HISTORY 

the presence or absence of a petiole. Describe 
accurately the veniation (condition in the bud), as 
shown by young leaves just unfolding. 

2. Suggest any advantage to the plant of any of the 
facts recorded under D, i. 

3. Compare the character of the leaves with that of 
any of the ferns. 

E. The Roots: 

I. Briefly state their location and fanctioiis. 

REPRODUCTI\^ ORGANS 

F. The StamimUe Cones: 

1. Describe their appearance, and, if the material is 
suitable, their distribution on the plant. 

2. Describe, accurately, the distribution of the micro- 
sporophylls (stamens) on the main axis, or stem, of 
the cone. 

3. Make drawings, natural size, showing (a) a surface 
\dew of the cone; (6) the cone as seen in longitudinal 
section? 

4. Remove one of the stamens. Describe it, and note 
the microsporangia 'pollen-sacs) attached to its 
lower siirface. Describe them, their number, dis- 
tribution, mode of attachment, and manner of 
opening dehiscence;. 

5. Make drawings (a) of a stamen with pollen-sacs 
attached; ih) of two or three pollen-sacs (X 10). 

6. The stamina te cone is in reality a primiiise fiawer. 
From this study, of what structure would you infer 
that flowers are a modification? 

G. The Male Gamet-ophyk: 

I. The young pollen -grain (microspore) begins to 
germinate before it leaves the pollen-sac, two di%'i- 



ZAMIA FLORID ANA 1 55 

•V 

sions of its nucleus taking place. By the first cell- 
division two cells are formed, one, the first prothal- 
lial cell, representing the vegetative portion of the 
male prothallus; the second, or antheridial cell 
(called the "antheridial initiaP' by some botanists), 
divides again, forming a tube-cell and a generative 
cell. By the division of the generative cell, the 
stalk-cell and body-cell are formed. The division 
of the body-cell gives rise to two sperm-mother- 
cells, and each of these latter become transformed 
into a motile sperm. 
2. Complete the following diagram of the above se- 
quence of cell-divisions: 

Microspore 
O 




First Proth. ^ " Anth. Cell 

Cell 

3. Mount several pollen-grains in water, and examine 
them under the high power. Describe their shape 
and contents. Draw. 

4. The study of the mature male prothallus, produced 
by the formation of a pollen-tube, will be omitted 
here. 

H. The Young Carpellate Cone: 

1. The youngest cones offered for study were collected 
about March i. 

2. Describe the cone, and the distribution of the mega- 
sporophylls (carpels) on its main axis, or stem. 
Draw, natural size. 

3. Carefully dissect^ off one of the carpels. Describe 

1 For economy of material, with large classes, excised carpels may be 
supplied. 



156 MORPHOLOGY AND LIFE HISTORY 

its form and surface characters, and note the num- 
ber, and place and mode of attachment of the large 
megasporangia (ovules) . Note their color. Draw, 
natural size. 
4. Do you find smaller, undeveloped ovules? These 
have probably not been pollinated. 
I. The Young Ovule: 

1. Is the ov}Ae enclosed by the carpel, or is it naked? 
State why Zamia is classed as a gymnosperm. 

2. At the end of the o\'ule, opposite its point of attach- 
ment, note the small, often slightly elevated, dark 
spot, which marks the place of the micropyle (small 
gateway), through which the pollen-grain passes 
in order to reach the pollen-chamber within. This 
process is called pollination. In Zamia, pollination 
occurs about Jan. i. 

3. Remove an oMile, carefully noting where and how 
it is attached to the carpel. 

4. Describe its surface and shape. How may the 
latter, in part, be accounted for? At the end 
opposite the micropyle obsen,'e the scar (hilum), 
where the o\"ule was attached. Draw.^ 

5. With the scalpel, make a slight longitudinal incision 
of the integument (wall) of the o\'ule, being careful 
not to cut too deeply, so as to injure the delicate 
structures \sithin. Describe the character of the 
tissue of the integument. 

6. The tissue next within the integument is the 
nucellus, or megasporangium. The integuments 
are outgrowths of the nucellus. 

1 Arrange all the drawings, showing the o\iile at different ages, serially, 
on a new sheet of drawing paper, so as to facilitate the comparison of the 
different stages, and to show at a glance the changes which the different 
parts undergo. 



ZAMIA FLORID ANA 1 57 

7. After making a longitudinal incision, very carefully 
remove the nucellus, noting the greater thickness of 
the tissue at the micropylar end. This tissue serves 
as nourishment for the germinating pollen-grain. 

8. Within the nucellus is the globular young female 
gametophyte, or endosperm. Describe and (from 
your reading in the text-book) account for its 
consistency. 

9. With the razor make a median, longitudinal section 
of the entire ovule. Study and draw, naming all 
the parts. 

/. Older Stages in the Development of the Ovule: 

1. Examine ovules collected about April i, as directed 
under /. Compare their size with that of the 
younger ovules. Observe the fleshy texture being 
assumed by the outer portion of the tissue of the 
integument, and the differentiation of a harder 
inner layer (endopletira) . 

2. Describe the changes which the nucellus has under- 
gone. Account for these changes. (The appear- 
ance of the nucellar tissue may be due, in part, to 
its disintegration by the growing pollen-tubes.) 

3. Remove the nucellus and describe the appearance 
of the endosperm. Note the slight depression in 
its micropylar end. What change has taken place 
in its consistency? Account for the change. 

4. With a scalpel cut away the endopleura, and then, 
with a razor, make a clean, median longitudinal 
section of the endosperm, and observe, imbedded 
in its micropylar end; two or more archegonia. 
These open into the depression mentioned above by 
a short neck, composed of only two cells. The short 
neck-canal may be seen if the section passes through 
a suitable plane. 



158 MORPHOLOGY AND LIFE HISTORY 

5. With a hand lens observe the wall of the arche- 
gonium, and within, filling the venter, the large 
ovum, or egg. » 

6. As outHned above (/, 1-4), examine and describe 
an ovule one month older (about May i), carefully 
noting the changes which the different parts have 
undergone. Observe especially the development 
of the hard inner layer of the integument. May 
this feature be of any advantage to the plant? 
If so, how? Does any of the nucellus remain? 
If so, describe. Note, in the depression of the endo- 
sperm, the openings into the archegonia. How many 
are there? Draw this depression as seen in end 
view. 

7. Construct a diagram of an ovule of this age as seen 
in median longitudinal section, carefully labeling 
all parts. 

8. Make a diagrammatic drawing of a cross-section of 
the same ovule passing through the venters of the 
archegonia. 

9. In ovules one month older (about June i) the sac- 
like proembryo may be seen, lining the walls of the 
venter of the archegonium, and, growing from its 
basal end into the tissue of the endosperm, the 
prominent suspensor, at the free end of which the 
embryo begins to develop. As the suspensor and 
embryo increase in size, a cavity is formed in the 
surrounding endosperm. This cavity results from 
the digestion of the endosperm tissue^ which goes 
to nourish the growing embryo and suspensor. 
Suggest how this digestion and subsequent nutri- 
tion may be accompHshed. 

10. Make a drawing of a median longitudinal section 
of the ovule at this stage. 



ZAMIA FLORID ANA 1 59 

K, The Seed: 

1. The seed matures about July i. Study the struc- 
ture of a ripe seed, comparing it in every point with 
the structure of the unripe ovule, as directed above 
{J, i-io). 

2. Note the soft, outer layer of the integument. 
Describe it. 

3. In cutting away the hard, shell-like inner layer 
(endopleura) be careful not to disturb the portion 
of the nucellus that fits like a cap over the mycro- 
pylar end of the endosperm. Now carefully lift 
this portion of the nucellus and observe the long, 
coiled suspensor attached to it, and (at its other 
end) to the projecting thick, round peg (hypocotyl) 
of the embryo. 

4. With the scalpel gradually remove one-half of the 
endosperm, until you expose the embryo (young 
sporophyte) imbedded in it. Is the embryo curved 
or straight? Is it now confined to the venter of 
the archegonium? 

5. Observe that the hypocotyl bears fleshy seed-leaves 
(cotyledons). How many are there? Compare 
their lengths. 

6. Does more than one embryo come to maturity in 
any one seed? 

7. When the sporophyte of Zamia begins to develop, 
is its growth continuous to maturity, or does a 
period of rest intervene between two stages of 
growth? Compare Zamia with the fern, moss, and 
Selaginella in this respect. 

8. Define a seed, and state how it differs from an 
unripe ovule, and from a spore. 

9. Suggest any advantage to the plant of the seed- 
habit. 



i6o momsiBssjoGS amd ussr wewobks 

L. NMtrUwmc 

1. Describe llie idalive alafity of liie maliiie sporo- 
ph^ aond llie gunetoplijfe Id kad an independent 
cxEtencc Is fbe gunetopiifte ever independent 
of file spasiagbytc? Does Ae spomplijte ever five 
parai^iirally on flie ganetopiiyte? 

2. Wlijdoesflieemfaripa-^anipl^teneedasi^pptyof 
food stoRsd in llie seed? 

3. Would it be of may f^edil advantage to Zmaum to 
3ia;vea,wdMevdopednialec«nc!tiipiiyte? Wbj? 

4. At borne vrite a detailed description of Ibeciiaii^es 
iindei^gane b^ a. stanA gnin, faonedin Ibe leaf of 
£ HI ';■- e carpe-li : 7 s ;>ampl^te, nnfil it bemmes 
zi:: :: :it riEst :: :it tiobrfo-spompliyte of flie 
next spoK^iLyte-gtitniioa- 

5. !.:ile 1 i:sr:Ei=^--:: -tfinc (i:£ir -:-:i 1:: 

spoffopi. ;• ". t ". : s I ■ : : : 1 1 v : t , 



Pinus laricio (Austrian pine) 

A. Classification: 

Division VI. Spermatophyta. 
Subdivision A. Gymnospermae. 
Class I. Pinoideae. 
Order. Coniferales (cone-bearing plants). 
Family. Pinaceae (pine family). 
Genus. Pinus (the pines) . 
Species, laricio (Austrian pine). 

B. Habitat: 

The Coniferales are widely distributed over the earth's 
surface, often forming extensive forests. The genus 
Pinus occurs in North America throughout Canada 
and the northern United States, from the Atlantic to 
the Pacific coasts. The white pine (Pinus Strohus) 
occurs from Canada south along the Alleghanies to 
Georgia, and west to Illinois and Iowa. The western 
yellow pine {P. ponderosa) extends south to western 
Nebraska, Texas, Mexico, and California. The long- 
leaved or "Georgia pine'' (P. palustris) is found near 
the coast from Virginia to Florida, and Texas. The 
spruce-pine (P. echinata) also occurs as far south as 
Florida, and in Illinois, Kansas, and Texas. Consider- 
able forests of it are found in southern Missouri. The 
loblolly pine (P. tceda) extends along the coast from 
Delaware to Texas and north up the Mississippi 
Valley to Arkansas. Pinus laricio is not native to the 
United States, but has been introduced into cultiva- 
tion, as has also P. sylvestris, the "Scotch pine," of 
northern Europe, and other species. 
Pine wood was formerly one of the most valuable and 

II i6i 



l62 MORPHOLOGY AND LITE HISTORY 

at the same time one of the cheapest of soft-wood 
timbers, but owing to an utter disregard of the prin- 
ciples of scientific forestry, it is now one of the scarcest 
and most expensive. Regions that were formerly 
extensively forested, and the center of a prosperous 
lumber industry, are now waste land, often occupied by 
tall stumps, and a source of no profit. It is not neces- 
sary to destroy the forests in order to obtain an abun- 
dant supply of lumber, pro\dded only that the crop be 
harvested in accordance with scientific principles. 
The conservation of the forests is one of the most important 
economic problems confronting aur country, and excellent 
opportunities are now offered for well-trained foresters. 

Vegetattve OrG.\2sS 
C. The Stem: 

1. In Finns the shoot, as usual, is composed of the 
stem and the leaves. The stem is di\dded into a 
main part, or tnmk, and lateral branches. The 
entire portion of the shoot, except the trunk, is 
designated by foresters as the crown^ of the tree. 

2. The following observations (C, 3-10) of the stem 
as a whole are to be made out of doors, recorded 
at this place in the laboratory notes, and handed in 
at the next class period. 

3. Designate the t^^pe of the trunk as excurrent [i.e., 
extending, entire from the ground to the apex of the 
tree), or deliquescent {i.e., extending entire for only 
a short distance from the ground, and then sub- 
di\iding into the numerous limbs and smaller 
branches of the crown^). 

^ The use of the term cro-j.n in this sense is quite different from its 
older use by plant anatomists to designate the region (usually at or near 
the surface of the ground) where the root and shoot join. 



PINUS LARICIO 163 

•V ■ 

4. Describe variations in the diameter of the trunk. 

5. Do you find prominent swellings (buttressing roots) 
at the base of the trunk? If so, suggest their 
possible advantage to the tree.^ 

6. Describe the outline of the crown as flat, conical, or 
cyhndrical. 

7. Describe the appearance of the bark. 

8. Note that the lateral branches appear to be given 
off in whorls, or circles, at regular intervals along 
the trunk. Observe closely and state whether 
these are true whorls {i.e.^ the component branches 
in exactly the same horizontal plane), or pseudo- 
whorls {i.e.y the branches not really in the same 
plane). 

9. Do you find enlargements on the under side of the 
larger limbs at the base? Suggest any advantage 
this may be to the Umb; the conditions resulting 
in their formation. 

10. Draw a diagram illustrating all points observed 
under C, 1-9. Make the trunk 15 dm. high. 
D, The Vegetative Branches: 

1. In specimens furnished, note the two kinds of vege- 
tative branch: The main or "long" branch, bear- 
ing scale-like leaves, and, in the axils (upper angle 
made by the leaf with the branch that bears it) of 
these scales, the dwarf branches, bearing the foliage- 
leaves or pine "needles." In what does the long 
branch terminate? 

2. The Long Branch, 

(a) Describe the arrangement (spiral) and dis- 
tribution of the dwarf branches on the long ones. 
(6) Note the rings of dry bud-scales or scale-scars 

*The conditions favoring the formation of buttresses should be dis- 
cussed in class. 



PINXJS LARICIO 165 

length each year? Find evidence that they 

do not. 
(b) Compare the number of needles borne by each 

dwarf branch. Is the number constant? On 

what part of the branch are they borne? 
{c) Note the bud-scales, some of which form a 

sheath about the bases of the needles. 
The Foliage-leaves. 

(a) Describe their shape. Are they differentiated 
into petiole and blade? 

(b) Make a drawing, natural size, of an entire leaf, 
and a diagram (X 10) of a cross-sectional view. 

The Terminal Bud. 

{a) Describe its color, coverings (bud-scales), 

and shape. Draw (X 3). 
{b) With the scalpel remove one of the bud-scales 

at its base. Describe and draw (X 5). 

(c) Now remove, one at a time, the remaining bud- 
scales, having care not to break or injure the 
tender inner tissues. 

id) Describe the place and mode of attachment 
of the scales. 

(e) Explain how they are adapted, in structure and 

position, to protect the bud. From what do 

they protect it? 

(/) Describe the color of the inner tissues. Can 

Pinus form chlorophyll in the dark? Explain. 

(g) Make a drawing (X 5) of the bud after the 
scales have been removed. 

Qi) With a sharp scalpel make a median longi- 
tudinal section of the bud. Observe the central, 
conical axis, bearing thin membranous scales. 
In the axile of each scale find a small knob-like 
outgrowth. 



l66 MORPHOLOGY AND LLFE HISTORY 

(i) Make a drawing (X lo) of the longitudinal vie^r. 
{k) Into what ^sill the bud develop? What will 

become of each of its parts? 
(/) How much of your specimen represents last 

year's terminal bud? The bud of year before 

last? 
{m) \\Tien the annual growth of a branch ends with 

the formation of a bud the growth is called 

determinate. Is the growth of the dwarf 

branches determinate or indeterminate? Of 

the long branches? 
£. Homologies: 

1. Organs which perform like functions are analogous 
to each other. Organs which correspond to each 
other structurally, i.e., which have the same mor- 
phological value, are homologous. For example, 
the flat, chlorophyllous stems of cacti and the foliage 
leaves of the maple tree are analogous, for they both 
function as organs of photosynthesis; but they are 
not homologous, for one is a stem, the other a leaf. 
The bud-scales of Pinus and the pine ''needles" 
are homologous, i.e., from the standpoint of struc- 
tural value (morphological standpoint) they are 
both leaves. But they are not analogous, for, 
whereas the ''needles" act as organs of photo- 
s}!! thesis, the bud-scales do not, as they have no 
chlorophyll. 

2. One of the most important, and often most difficult, 
problems of morpholog}' is correctly to interpret 
the structural value of an organ; in other words, to 
recognize homologies; for any organ may be pro- 
foundly modified, and appear so disguised as to 
make it extremely difficult to recognize its morpho- 
logical significance. Pinus furnishes an excellent 



PESrUS LARICIO 167 

illustration of the modification of organs for various 
functions. 
3. Enumerate all the homologs of the foliage-leaf 
found thus far on Pinus, and show why the organs 
you name are homologous. 

Reproduction 

F. The Staminate Cone: 

1. On which portion of the vegetative branch are the 
staminate cones borne? Do they extend clear to 
the tip of the branch, i.e., are they ever terminal? 
In what does the tip of the branch that bears 
them terminate? Ascertain their length and 
greatest diameter in millimeters. 

2. Are the cones subtended by {i.e., borne in the axil 
of) a scale-Uke leaf ? Note whether they are sessile 
or stalked? 

3. Observe the spiral-like arrangement of the micro- 
sporophylls of the cone. 

4. The staminate cones are modified branches. To 
which of the vegetative branches are they homolo- 
gous? 

5. Make a diagram (X 2) showing the mode of attach- 
ment of the cone and the subtending scale. 

6. With a razor bisect a cone longitudinally and ob- 
serve the central axis, bearing the microsporophylls, 
or stamens. 

7. With the aid of a hand lens, or dissecting micro- 
scope, observe the short stalk of each stamen and, 
on the under (dorsal) side of the broadened stalk, 
two small pouches, the pollen-sacs (microspor- 
angia), containing pollen-grains. 

8. Make a diagram (X 10) of the cone as seen in longi- 
tudinal section. 



1 68 MORPHOLOGY AND LIFE HISTORY 

9. Remove an entire stamen and observe that the 
tip of it is turned up so as to fit over the end of the 
stamen next above it. Suggest any advantage in 
this arrangement. 

10. Make a drawing to illustrate this feature. 

11. Make a cross-section of the stamen and ascertain 
of how many pollen-sacs it is composed. Draw. 
The pollen-sacs of the stamen constitute the anther. 

12. The structure of the stamina te cone shows it to be 
in reality a simple flower. It is homologous to the 
staminate flower of some of the higher plants. To 
what in Zamia is it homologous? 

G, The Young Male Gametophyte: 

1. Mount several mature pollen-grains in water and 
examine with the high power.. 

2. Observe the body of the grain, and the two lateral 
wing-Kke expansions, developed from the outer coat 

of the pollen-grain. Suggest their use. 

3. Within the grain observe the tube-nucleus near the 
center, and the generative cell near the wall farthest 
from the wings. Look for the prothallial cell, 
which frequently may be seen between the wall of 
the grain and the generative cell. 

4. Make a drawing, 25 mm. broad, showing all features 
observed under G, 1-3. 

5. The nuclear and cell-divisions which give rise to 
these structures are steps in the germination of the 
microspore. Into what does the microspore of the 
heterosporus pteridophytes develop by germina- 
tion? To what, then, in Isoetes or Selaginella, is 
the mature pollen-grain of Pinus homologous? 

6. If prepared microscopic shdes are available, more 
detailed study may be made of the structure of the 
pollen-grain. 



PINUS LARICIO 169 

> ■ 

E. The Young Carpellate Cone: 

1. On which internode of the vegetative branch are 
the carpellate cones borne? On what part of the 
branch? Do they occur singly or in clusters? As 
terminal or as lateral outgrowths? 

2. Note that each carpellate cone is borne at the tip 
of a stalk. Describe any outgrowths on this stalk. 

3. Describe the attitude of the cone at the time of 
pollination, as erect or pendant. 

4. Observe the spiral arrangement of the cone-scales, 
somewhat more marked than in the staminate cone. 
In fresh specimens the cone-scales are slightly 
separated from each other at the time of pollina- 
tion. Explain the advantage of this. 

5. Make a drawing (X 2) of the cone with the stalk 
that bears it. 

6. Make a median longitudinal section of the cone and 
stalk, and represent by a drawing all parts seen. 

7. Carefully dissect off one of the central cone-scales, 
being sure to note which is the inner (ventral) and 
which the outer (dorsal) surface of the scale, and 
observing the membranous bract which subtends it. 

8. On the inner surface of the scale, near the base, 
observe with the hand lens two ovules, each with 
two little prongs, between which is the pollen- 
chamber; between and above the ovules a pointed 
outgrowth. 

9. Make drawings (X 10) of the ovuHferous scale as 
seen (a) from the side; {b) from the outer surface, 
showing the bract; (c) from the inner surface, 
showing the ovules. 

10. The ovules are megasporangia surrounded by a 
protecting integument. 

11. There is some evidence for considering the ovnli- 



170 MORPHOLOGY .A2vD LIFE HESIOSY 

ferous scale and :he :ra:: that subtends it as a 

megasporophyll, or carpel. On the basis of this 
in terpre : a :: : r. the bract would be bomolog : u s : : : - e 

ligiile in hjc^^s :: 5^"::^;f'":. Bu: ::Jit: :a::.s 
argue against tnis :ne::y, ana leaf :: iizeren: 
interpre:.a:::ns. s: :ha: :ne eia:: hrmiliry :: :ne 
organ is in a:u;:, F:ss::>.' i: represents :~: mega- 

sporcnnyils :r :arnels, I: s: . "-e mus: interpret the 

p;ilen-tu:e tegins, Its growth is very sh~, n:"-ever. 
untii the follo~hng siring, "hen the gr:~th ":e times 












tissue, The generath.-e :eh iiviies int: a body-cell 

and a stalk -cell, ana the nu ileus it the :iay-ieil 

again di'.-ides inti t-u sperm -nuclei. 
K. The ¥irr::^Qy,.:-_:^-r ■,:..: 

Near the tinte it tiihlnattin the m^a^wie consists of 
one uninu ilea te eh tne i ne-:e"e istagpcrf the embryo- 

sac . By reneatea nuilear-:l hsitns the nudeos of the 
megaspire gives rise ti a large nuntter of nuclei, which 

at nrst ue tree in tne surriunaing i titi.asin:bxitlater 
each o: these nuclei irianiaes atiut itseif a ceQ, 
surrcuniied by ceh-"-ahs, The tissue thus formed 
within the ent:rv:-sai, ana enlargea ;y rr:~uh, tims 
the young fentale gantetinhyte enaisnerni;. The 
megasporangi'um,. surriuniing the ena: saerm. is called 



PINUS LARICIO 171 

> ■ 

the nucellus, as in Zamia, and both these structures are 
surrounded by a protecting envelope, the integument. 
The pollen-chamber lies between the tip of the nucellus 
and the integument. The micropyle leads through 
the integument to the pollen-chamber. In the pol- 
Hnation of Pinus the entire pollen-grain passes into 
the pollen-chamber through the micropyle. 

L. The Ovule: 

The endosperm, nucellus, and integument together 
form the young ovule. Nearly one year is required 
for its development to the stage described above. In 
the second spring, while the pollen-tube is rapidly 
elongating, and the nuclear divisions noted above are 
taking place within it, several archegonia develop in 
the micropylar end of the endosperm. In the venter 
of e^ach archegonium lies the large egg. 

M. Fertilization: 

Eventually the pollen-tube enters the neck of an arche- 
gonium (compare with the process in Zamia and other 
Cycads), its contents are discharged into the venter, 
and one of the sperm-nuclei fuses with the nucleus of 
the egg. Thus fertilization is accomplished, about one 
year after pollination. The transfer of the sperm- 
nucleus to the egg by means of a pollen-tube is called 
siphonogamy, and plants in which this occurs, 
Siphonogamia. 

The one-year-old cone, to be studied next, represents 
the stage of development at about the time of fertiliza- 
tion. The sperms of Pinus are non-motile. 

N, The One-year-old Carpellate Cone: 

1. Compare the position on the branch, and the atti- 
tude of the one-year-old cones with that of the cones 
at the time of pollination. 

2. Study these cones as directed above {H^ i-n), com- 



172 MORPHOLOGY AND LIFE HISTORY 

paring the older and the younger organs. En- 
deavor to explain any differences observed. 
3. Record the length and greatest diameter of the one- 
year-old cone, and make a drawing of it, natural 
size. 
O. The Two-year-old Carpellate Cone: 

1. Record, its position on the branch, its attitude, and 
dimensions. Compare it, in these points, with the 
young, and one-year-old cones. Draw, natural 
size. 

2. Make dra-^angs of a detached scale as seen from 
(a) the outer (dorsal) surface, (Jb) the inner (ventral) 
surface, {c) the side. Describe any changes 
observed in the appearance and relation of the 
various points. 

3. Note that the ovtile has developed into a winged 
seed. 

P. TheSeed:^ 

1. The seeds are usually shed from the pine cone during 
the third summer, about two years and a quarter 
after poUination. 

2. Record the dimensions, shape, and character of the 
surface of the seed. The small depression in the 
smaller end of the seed locates the micropyle, which 
is now grown together. Draw, natural size. 

3.' Let fall from a height of several feet a seed of some 
species having wings still attached, and note the 
approximate time required to reach the ground. 
Remove the wing and repeat the observation. Sug- 
gest a use of the wing. Is it very firmly attached 
to the seed? 

4. Remove the tough, outer seed-coat (testa), which is 

1 The large seeds of the nut-pine, Pinus edulis, or of Pinus pinea, may 
advantageously be used for this study. 



PINUS LARICIO 173 

the mature integument, referred to in K and L 
(p. 1 70-1 71). The integument is analogous to an 
indusium. Why? 

5. Underneath the testa, observe the thin, membran- 
ous inner seed-coat, formed by a separation and 
differentiation of an inner layer of the tissue of the in- 
tegument. Describe its color and surface-character 
as seen under the hand lens. Compare with Zamia. 

6. Observe the small hole through the micropylar end 
of the inner coat. What does this represent? 

7. Remove the inner seed-coat, having care not to dis- 
turb the brownish, membranous cap on the micro- 
pylar end of the kernel. This cap is the remains 
of the nucellus (megasporangium) . Note the modi- 
fication of its tissue at the place through which the 
pollen- tube passed on its way to the embryo-sac. 
The remainder of the nucellus was consumed by 
the female gametophyte during the development of 
the latter. 

8. What is the homology of the white, fleshy kernel 
of the pine seed. 

9. Make a drawing (X 4) of the endosperm and nu- 
cellus. 

10. Remove the nucellar tissue. Is it firmly attached 
to the endosperm? Describe the appearance of the 
endosperm under the nucellar cap. 

11. Very cautiously separate the endosperm into longi- 
tudinal halves. Begin the dissection at the end 
opposite the micropylar end so as not to injure the 
embryo-sporophyte within. 

12. Observe that the embryo lies in a distinct cavity or 
chamber, its tissues being quite distinct, anatomic- 
ally, from those of the gametophyte. Can you ac- 
count for the formation of this cavity ? 



174 MORPHOLOGY AND LIFE HISTORY 

13. Note that the embryo is composed of a main axis, 
bearing a whorl of cotyledons borne near one end. 
Can you detect distinct regions of the axis? If so, 
how many, and how are they distinguished? How 
many cotyledons are there? Is the number always 
either odd or even? 

14. Observe that the embryo is attached at the end 
opposite the cotyledons to a slender filament, the 
suspensor. At this end of the embryo-chamber 
may frequently be seen the disorganized remains of 
other embryos that failed to develop. In rare 
instances two embryos develop in one seed. This 
is called polyembryony, a condition very common 
in lemons, and other citrous fruits. 

15. Make a drawing of the young sporophyte, 50 mm. 
long. 

16. Make a median longitudinal section of the embryo, 
and observe that the portion of the axis below the 
cotyledons (hypocotyl) is encased in an outer, 
strongly developed root-cap, which completely en- 
closes the hypocotyl. Note further that the coty- 
ledons are borne on the hypocotyl. From its op- 
posite end (radicle-end) the tap-root will develop. 
The hypocotyl is the first internode of the sporo- 
phyte. Where is the first node? 

17. At the summit of the axis, above the cotyledons and 
surrounded by them, observe the conical epicotyl. 
It will develop into the second and subsequent 
internodes. Explain the meaning of the term 
epicotyl. 

18. Construct three diagrams (X 5) showing (a) the 
entire seed in longitudinal section (the embryo not 
sectioned); (b) sl cross-section of the seed, passing 



PINUS LARICIO 175 

through the cotyledons and epicotyl; (c) a cross- 
section of the seed passing through the hypocotyl. 
Q. The ^^ Germination^^ of the Seed: 

1. Observe specimens of seeds and seedlings represent- 
ing various stages of germination. 

2. Describe (a) the changes that the various parts of 
the seed undergo, in shape, size, and position; (b) 
the manner in which the seedling breaks through 
the surface of the soil, and the advantage of this; 
(c) the relative rate of early growth of the root and 
shoot, and the significance of this; (d) color-change 
in the cotyledons, its significance and whether or 
not it can take place in darkness; (e) the fate of the 
endosperm, and the evident role of this tissue; (/) 
the manner of shedding the seed-coat; (g) the place 
of development and character of any new organs. 

3. Compare the germination of a seed, with that of a 
spore. What, in reality, is the germination of a 
seed? 

R. General Questions: ' 

1. To which alternating generation does the pine tree 
belong? 

2. In a well- worded paragraph compare the relation 
of gametophyte and sporophyte in the moss, fern, 
Isoetes (or SelagineUa)y and Pinus. 

3. State the relative prominence of the sexual and 
asexual generations in plant-groups of successively 
higher organization. 

4. When the young sporophyte of Pinus begins growth 
does it grow continuously to maturity, or does a 
period of rest intervene? Compare it with Isoetes 
or Selaginella in this respect. 

5. What changes would result in the formation of a 
seed in Isoetes? What interferes with seed-forma- 



176 MORPHOLOGY AND LIFE HISTORY 

tion in that group? What changes would interfere 
with seed-formation in Finns? 

6. Define a seed. State several advantages to the 
plant of the seed-habit. 

7. To what, in the fern, is the endosperm of the pine 
seed homologous? To what in the moss? To 
what, in Isoetes or Selaginella, is the pollen-grain 
homologous? To what in the fern? State, with 
reasons, whether the leaves of the moss-plant are 
homologous or analogous (or neither) to pine need- 
les. In like manner, compare the organs of fixation 
of the moss-plant, of the fern-plant, of the fern- 
prothallus, and of the pine tree. 

8. Diagram the life cycle of Finns as directed for 
Isoetes {E, 3, p. 139), substituting ^^( = pollen- 
grain) for wf( = microspore), and e5( = embr}'o-sac) 
for W€( = megaspore). 



Trillium (Wake-robin) 

A. Classification: 

Division VII. Spermatophyta. 

Subdivision B. Angiospermae (seeds enclosed in an 
ovary) . 
Class I. Monocotyledoneae (embryo with one 
lateral cotyledon). 
Order. Liliales (lily order). 
Family. Liliaceae (lily family) . 

Genus. Trillium (Latin tres, three). 
Species, (e.g., sessile) (sessile flowered 
, trillium).^ 

B. Habitat: 

All species of Trillium occur in the woods in early 
spring, and the genus has a geographic range extend- 
ing from Nova Scotia westward to Manitoba, and 
southward as far as Florida. 

1 Any species of Trillium may be used, with minor changes in the direc- 
tions; or, in fact, any other convenient genus of the Liliaceae. 

Note. — There are nearly 25,000 different species of Monocotyledons. 
The order Liliales, comprising about 5,000 species, contains the most 
highly developed types. The lower Monocotyledons have naked flowers 
{i.e., no sepals and petals), with the parts spirally arranged, as in the Gym- 
nosperms. The higher ones have the parts of the flower arranged in con- 
centric circles or cycles, five in number (pentacyclic), with usually three 
members in each cycle. Our knowledge of the monocotyledons is not yet 
adequate to make possible a satisfactory classification. Taxonomists 
diflFer in various points. The authors of Gray's "New Manual" (7th 
Edition, 1908) subdivide the Liliaceae into Tribes. Trillium is in the tribe, 
ParidecB. Britton ("Manual of the Flora of the Northern States and 
Canada") and others, divide the Liliaceae, as given in Gray, into four or 
more families, the trilliums being in the ConvallariacecB, or Lily-of-the- 
valley family. 

12 177 



1 78 MORPHOLOGY AND LIFE HISTORY 

C. The Shoot: 

1. General. 

(a) Note its division into a main, thickened under- 
ground part (rhizome), bearing numerous roots, 
and a long slender aerial branch. 

2. The Rhizome. 

{a) Describe its attitude (horizontal or erect), and 
its general appearance. Compare Trillium 
with the fern in this respect. 

(ft) Are there branches, besides the aerial branch? 

(c) Note the thin membranous scales near the 
apical end. Record their number and position. 
Carefully remove them with the scalpel. What 
purpose may they serve? What is their 
homology? Make a drawing of one (X i). 

id) Observe the nodes and intemodes. What 
do the nodes represent? Note the remnants of 
the old scales at each node. Compare the 
lengths of the intemodes. What is the mean- 
ing of this? 

ie) Describe any other scars on the rhizome. Are 
they on nodes or intemodes? What do they 
represent? 

(/) State, with reasons for your opinion, the age 
of your specimen. 

3. The Aerial Branch. 

(a) Describe its general appearance, shape, length 
(compare several different specimens), color- 
ation (color-pattern), and presence or absence 
of branches. 

(6) At which end of the rhizome is it borne? Is 
it a terminal or a lateral outgrowth? Is it an 
axillary organ (i.e., borne in the axil of a leaf), 
or not? On a node or an internode? 



TRILLIUM 179 

(c) Make a drawing 20 mm. in diameter, showing 
the distribution of the fibro-vascular btmdles 
as seen in cross-section. 

{d) What does the branch bear at its summit? 
Do you find any exceptions to this? 

D. The Roots: 

1. Describe their distribution on the root-stalk. Do 
they occur on both nodes and internodes? State 
the significance of the observed distribution. 

2. Record the presence or absence of branching. 

3. Compare the appearance of new roots with that 
of older ones. On what part of the rhizome are 
they borne? 

4. Describe the surface appearance of older roots. 
Remove a root 3 to 4 cm. long, hold it by each end 
and gently pull (not hard enough to break the 
root). How does this affect the surface appear- 
ance? How do you think the original feature 
was produced? 

5. With the scalpel cut a root squarely off near its 
base and observe the cross-sectional view. Dis- 
tinguish three tissue-systems: {a) the epidermis; 
{b) the central cylinder; (c) between (a) and (6), 
the cortex. 

6. Peel down a strip of the epidermis, and observe 
whether the wrinkling is confined to it or not. 

7. Make a drawing, twice natural size, showing the 
external features of the rhizome, together with a 
portion of the aerial branch, and roots. 

E. The Young Terminal Bud:^ 

I. Carefully remove the aerial branch and surrounding 
scales and observe the terminal (apical) bud. 

^ On account of the large amount of material required, it is desirable 
to make E and F class demonstrations by the instructor. 



l8o MORPHOLOGY AND LIFjE HISTORY 

2. Describe its color, shape, attitude, and the relation 
between it and the base of the aerial branch. Draw 

(X 2). 

F, The Mature Terminal Bud'^ 

1. Use material gathered in late autumn, and care- 
fully dissect away the outer bud-scales. Identify 
the parts found within. 

2. Make careful drawings, and interpret the signifi- 
cance of this observation. 

G. The Foliage-leaves: 

I. Describe the number, location, and arrangement 
of the foliage-leaves. Are they petiolate or sessile? 

2., Observe: 

(a) The coloration (described, for T. sessile^ as 

"blotched"). 
Q)) The outHne of the base, apex, and margin. 
{c) The venation. 
E. The Flower: 

1. On what part of the shoot is it borne? Record 
the presence or absence of a flower-stalk (peduncle). 
Explain the significance of the specific name of 
this species {T. sessile). Has the flower an odor? 
If so, describe it. 

2. Observe. 

(a) The outer circle of parts (calyx) composed 
of separate sepals. How many sepals are 
there? Describe them as you did the leaves. 
Note. — The term calyx comes from the Greek 
word kalyx, a cover; the verb is kalypto, to 
cover. What organ of the moss has its name 
derived from the same source as calyx? 

(b) The circle of parts (corolla) next within the 
the calyx, composed of separate petals. How 



TRILLIUM l8l 

many petals? Are they opposite or alternate 
with the sepals? Record their color in fresh 
(not preserved) specimens. Describe a petal 
as you did the leaf and sepal. 

(c) With the corolla, a circle of three microsporo- 
phylls (stamens) each opposite a sepal. By 
carefully bending back (but not removing) 
the sepals and petals, observe whether or not 
the other stamens are in the same circle as 
the first ones, or in an inner (higher) circle. 
Describe their location with reference to the 
petals- Record the total number of stamens. 
Note that each stamen is composed of: 

(i) A stalk (filament), bearing at its tip, 

(2) An anther, composed of marginal, linear 
pollen-sacs (microsporangia), and connect- 
ing tissue (the connective). Observe 
whether the connective is prolonged be- 
yond the sporangia. Note that the pollen- 
sacs dehisce (open) on the inside (i.e., are 
introrse). Describe their manner of de- 
hiscence. 

(3) What do the pollen-sacs contain? De- 
scribe its color. 

(d) The central pistil composed of : 

(i) The basal ovule case (ovary) . How many 
angles has it? How many lobes? 

(2) The relatively long styles. How many? 
Their inner surface is modified into 

(3) A stigma. Describe this stigma tic surface 
as seen both with unaided eye, and under 
the low power. Usually numerous pollen- 
grains may be seen adhering to it. What 
process has therefore taken place? 



1 82 MORPHOLOGY AND LIFE HISTORY 

(4) The ovary is thus seen to be, not simple, 
but compound. It is composed of three 
carpels, bearing ovules. Since the ovules 
are megasporangia, what is the homology 
of the carpels? 

3. Look up in the dictionary, and record at this point, 
the derivation of the names of the various parts of 
a flower, studied above. 

(a) It is important to note: (i) That the various 
cycles are each composed of the same number 
of parts; (2) that the parts of the various 
cycles alternate with each other. 

(b) When the other organs of a flower are inserted 
below the pistil they are said to be hypogynous. 
Is this true of Trillium? 

(c) The more or less enlarged end of the stem (or, 
- in non-sessile forms, of the peduncle) on which 

the organs of the flower are inserted, is the 
receptacle. 

4. Make drawings as follows: 

(i) A sepal (X i); a petal (X i); a stamen (X 4) 
(both dorsal and ventral views); an imagined 
cross-section of an anther taken through the 
middle (X4); the pistil (X4); an imagined 
cross-section of the pistil (X 4). 

(2) A ground-plan of the flower, 5 cm. in diameter, 
first drawing five equidistant concentric cir- 
cles, and filling in the plan as directed by the 
instructor. 

(3) An imaginary longitudinal section of the flower 
(X2). 

5. Compare the length of the stamens with that of 
the pistil. Carefully consider and state the rela- 



TRILLroM 183 

■v ■ 

tive probabilities of self-pollination and cross- 
pollination. 

/. Non-sexual Reproduction: 

1. Non-sexual reproduction in Trillium is confined to 
the growth of the persistent, underground rhizome. 
This organ is thick and fleshy, serving for the storage 
of food. 

2. Note the ridges and scars on its surface. 

3. What develops each year at the growing end? 

4. A plant that is continued indefinitely, from year to 
year, by means of a persistent root or stem, or both, 
is a perennial; one that persists for two years only, 
setting seed and dying at the end of the second sea- 
son is a biennialj plants that set seed and perish at 
the end of one season are annuals. Name illus- 
trations of each of these three classes of plants. 

K. Sexual Reproduction: 

1. Microspores. 

(a) Mount in clearing fluid (or water) on a slide 
some of the pollen from an anther. 

(b) Observe (first under low, then under high power) 
the individual pollen-grains. Describe their 
color and shape, and note the network of 
ridges on the surface of each. 

(c) By carefully focusing on individual grains there 
may readily be detected in some of them one 
nucleus, in others, two. Those in the one- 
nucleate stage are mature microspores. 

2. Male gametophyte. The division of the microspore- 
nucleus is the first stage in the germination of the 
spore. To what do microspores, when they ger- 
minate, give rise? What, therefore, is the homol- 
ogy of the bi-nucleate pollen-grain? 

(a) The larger nucleus is the tube-nucleus, and 



l84 MOSFHOLOGrT AND IIFB HESTQRY 

presides over the development of the poflen- 
tobe. The smaller is I'zt generatiye nucleus.. 

(6) Make drawings, 2 cm. in i:3.ne:r: :; a micro- 
spore and of a male gamet<^hyt^ labding aU 
parts. 

(c) After pollinatioii, the formation of the pollen- 
tube takes place. This is usually spoken oi as 
the ' ' germination of the polkn-grain." 
The tube emerges throng one of several weak 
places in the wall of the grainy grows down 
throug^i the tissues of the style, digesting its 
channel as it proceeds, or, in some spedes, fol- 
lowing a canal already formed throng the 
style. 

The generatrre cell reiieTativenncleiis with its 
"::;::::: .1 sir : 11 ~ s i : wn the poHen-tnbe, 
ana ai\"iaes into cwo non-motile sperm celte. 
In some species, e.g., Sambucus, e.ie: this 
division occurs before the tube devel : ^ 5 The 
pollai-tabe passes through the miciopyle; and 
discharges the spaTOrceDs near the ^g. One 
of the qierm-nucki fuses with the ^g-nudeos, 
thus effecting fertilization. 

{d) For convenience in handliiig material the 
observation oi the finer structure of the anth^ 
and pollen will be defored until after the 
microsa^ic study of the ovary and ovules (3, 
bdow). 
3. M^asporopky^ and Megasporamgia. With a sharp 

sca]^)d or razor make a median cross-section of the 

ovary and observe: 

(a) Its outline. Each of the lobes r^resents the 
section of one of the carpels negasporoph}^). 



TRILLIUM 185 

which together compose the tri-carpellate, 
compound ovary. 

(b) The number of compartments, ("cells"). Do 
the septae (walk) that separate them meet in 
the center? Compare the number of cells with 
the number of carpels. 

(c) The placentae (sing. , placenta) , or surfaces of the 
septae to which are attached. 

(d) The ovules. Do the ovules lie in a vertical or 
in a horizontal plane? Are they few or numer- 
ous? In Trillium the ovules are borne on 
parietal placentae. 

(e) The funiculus (stalk) by which the ovule is 
attached to the placenta. Observe (using 
magnifier) that the ovules have curved through 
180°, bringing their apical (micropylar) ends to 
their base or point of attachment to the fun- 
iculus. They are thus anatropous ovules. 

(f) Make a drawing, 4 cm. in diameter, showing 
the ovary (and ovules) as seen in cross-section. 

4. Histology of the anther. Development of the pollen. 

(a) Use prepared slides. The sections on these 
slides are triple-stained with safranin, gentian- 
violet, and orange. By this means the various 
parts of the cell are given different colors, the 
cytoplasm a grayish tinge, the nucleolus and 
chromatin threads in the nucleus red, starch 
grains a deep blue. 

Using slides showing the microspore-mother-cell 
stage of Lilium canadense, or other convenient 
plant, 

(b) Observe the outline of the section as a whole. 

(c) The central portion is the connective, contain- 
ing^a vascular bundle. 



1 86 MORPHOLOGY AND LIFE HISTORY 

(d) Opposite the connective may often be seen a 
cross-section of the filament, with its vascular 
bundle. 

(e) The numerous, conspicuous blue-stained bodies 
are starch grains. 

(f) Note the epidermis, one cell thick. Does it 
cover the entire surface? Does it contain 
starch grains? Find numerous stomata, each 
with a small, imderlying air-space. 

(^) At each side of the section will be seen two 
sporangia, containing the large microspore- 
mother-cells (pollen-mother-cells), with promi- 
nent nucleus. Observe the network of chrom- 
atin within each of these nuclei. The mother- 
cells adhere more or less closely, depending 
upon age. Their final separation from other 
cells, and from each other, marks the first 
separation of the gametophytic from the 
sporophytic generation. The mature micro- 
spore-mother-cell is the first stage in the develop- 
ment of the male gametophyte {cf. 6 (a). 
below, p. 1 88). 

Qi) Around the mother-cells note a layer of elong- 
ate cells, radially arranged, and with nuclei 
more or less disorganized. These are the 
tapetal-cells. Together they form the tapettmi. 

{i) Between the tapetum and epidermis lie the 
middle layers of cells forming the wall of the 
sporangiimi. How many cells thick is it? 

{k) Make a drawing 8 cm. in longest measure, 
showing all features observed under 4, {a)-{k) . 

(/) By two successive divisions each pollen-mother- 
cell forms four microspores (young pollen- 
grains). They thus arise in tetrads. 



TRILLIUM 187 

Using slides showing pollen-grains, observe : 

(m) The more advanced disorganization of the 
tapetal-cells, including the breaking down of 
their cell-walls, and the fragmentation of their 
nuclei into two or more. These cells serve 
to nourish the spore-mother-cells. 

(n) The microspores. Do they lie free or con- 
nected? Describe their shape, surface-features, 
and number of nuclei. 

(o) State again the first stage in the germination 
of the microspore. What is the resulting 
structure? What is its homology? 

Megasporangia; megas pore-mother-cell. 

Using prepared slides showing the megaspore- 

mother-cell, observe: 

(a) The outline of the ovary as seen in cross-section. 

(b) The presence or absence of an epidermis; 
of stomata. 

(c) The "cells" of the ovary, each containing, in 
the section, 

(d) Two young ovules (megasporangia). Are the 
ovules straight or curved? 

At this stage the tissue of the ovule is chiefly 
nucellus, but soon there develops at the base 
of the ovule, outside of the nucellus, 

(e) The inner integument, which grows up around 
the nucellus, leaving at the summit only a 
small passage, 

(f) The micropyle. Outside the inner integument 
there usually develops 

(g) An outer integument. In anatropous owdes 
the development of the outer integument 
wholly or partially fails on the side where the 
funiculus adheres to the ovule. At the summit 



1 88 MORPHOLOGY AND LIFE HISTORY 

of the nucellus (apex of the ovule) is seen the 
large 

Qi) megaspore-mother-cell (embryo-sac-mother- 
cell), with very prominent nucleus and 
nucleolus. 

(i) Make a diagram of all that you have observed 
under 5, {a)-{h), filhng in the details for one 
ovule. 

6. Development of the Megaspores. 

{a) Like the microspore-mother-cell, the megaspore- 
mother-cell of Trillium divides twice, giving 
rise to four megaspores (tetrads), but only 
one of these megaspores develops a gametophyte. 
This spore enlarges, and by three successive 
divisions gives rise to an eight-nucleate female 
gametophyte, the embryo-sac. Three of these 
nuclei organize antipodal cells at the basal 
end of the embryo-sac, and three of them 
organize cells at the micropylar end. One of 
the latter is the egg, the other two thesynergids. 
The two remaining nuclei fuse near the center 
of the embryo-sac, forming the endosperm- 
nucleus (sometimes called definitive nucleus) y 
but the endosperm does not develop until 
after the fertilization of the egg. 

(6) Unlike the microspores, the megaspores, in 
angiosperms, never become free, independent 
cells, but always retain an intimate physiolog- 
ical connection with the sporophyte of the 
next preceding genera tioji (cf. 4(g), above). 

7. The Embryo-sac. 

(a) Using prepared slides, study the embryo-sac 
in its two- to eight-celled stages, identifying 
the cells mentioned in 6 above. Draw. 



TRILLIUM 189 

X". Development of the Embryo: 

I. After fertilization (/, 2, (c), p. 184), the oosperm 
develops the embryo-sporophyte, and while this 
is in progress the endosperm-nucleus, by successive 
divisions, develops into endosperm which surrounds 
the embryo, and will serve to nourish it when it 
re-awakens, at the ''germination" of the seed. 

L. Fruit and Seed: 

1. Meanwhile, as a result of fertilization, the ovary 
resumes growth, and develops into a fruit (ripened 
ovary), while the ovule enlarges and undergoes 
numerous changes, ripening into a seed. 

2. In a concisely worded paragraph, tell what a seed 
is, stating to which of the alternating generations 
the seed-coats, endosperm, and embryo belong. 

M. Nutrition: 

I. Discuss the nutrition of both the gametophyte 
and sporophyte of Trillium, as suggested above 
(Z, 1-4, p. 160) for Zamia. 
N. Tabular Review: 

Fill in the tables below (pp. 190 and 191), by placing 
an X in the proper space, then state, in a well- 
worded paragraph for each table, what may be 
learned by an inspection of it. 



190 



MORPHOLOGY AND LIFE HISTORY 



Table III.— ( 


Comparison 


r OF Gametophytes 








Plant 


s 

ft 

(0 

Pi 


05 

1 

>, 

to 




ca 

■(J 

to 




to 
^3 

bs 

43 
u 

•d 

c 

8 

to 

to 4J 

«« S 


Can exist independ- 
ently of the sporo- 
phyte 




u 
•ri 4) 

''I 

>i to 


ll 
m ft 



>.ft 

^^ 


to 

3 

'0 

8 
c 



to 

3 


8 

5 


X 

2 

^ft 

as 

0^ 


Has both vegetative 
and rep roductive 
functions 


CO 

a 


1 


Riccia 


I 


2 


3 


4 


5 


6 


7 


8 


9 


10 


II 


12 


13 


Anthoceros 




























Sphagnum 




























Polypodium 












' 
















Equisetum 




























Lycopodium 




























Selaginella 




























Isoetes 




























Zamia 




























Pinus 




























Trillium 

























































MORPHOLOGY AND LIFE HISTORY 



191 



AreAO 
av m pasoput spaag 


o» •••••••••• • 

IH 


itlBAO UB 

UT pasopui :;ou spsag 


00 • • • • • 

tH 


spaas saonpojj 


r» 

M 


spaas ou saonpoj<j 


vO • • • • • 


snojodsojai^au 


V> ' • ' 

n 




snojodsouioji 




a^Buitaopajd 
suoi:;ounj SAi^^Bi^aSa^ 












a:^BUimopajd 
suot:^outijaAi;onpojda-y 


w " . . . • 

H 


uoT:^B3'Bdojd 
[BnxasB JO ' ajqBdBQ 






M 


a^Aijdo:^auiB3 
UO OJ^TSBJBd ituotj^ 








IH 




a:^Aiido^auiB3 
UO opiSBJBd ^l^iv^ 




O' '.'.'.'.'.'.'.'.'.'. '. 




a:;Aqdo:^auiB3 jo 
;uapuadapui ^sixa ubq 




00 '.'.',','.'.','.'.'. '. 




sanssi:} Sui^^onpuoo sbjj 




t>. 




Ijos aiji. xnojj 
:).uauiiiSTanou s a sj b x 






! . ! . . 


b:^buio5.s sbjj 


•« ! I ! ! ! ! ! I ! I ! 


Xliiildojoxtio SBH 


"^ '.'.'.'.'.'. I '.'.'. '. 


sajidsa-a 




n '.'.'.'.'.'.'.'.'.'. '. 


A%iixivem jo 
aSB^^spadopAap ^Xii3iii 
ajoui B 0% oiuoXiq 
-uia tiB qSnoiq:}.' sassB<j 




M . . . . I . ! . . I I 


aSB^S 3IUO 

-itjquia jt|iBT:^uassa'uB 
puoAaq sassBd J^A^Jf^I 




M 






Riccia 

Anthoceros 

Sphagnum 

Equisetum 

Lycopodium 

Selaginella 

Zamia 

Pinus 

Trillium 



